Before I begin, I would like to note that Rokkr is a singular word that has multiple meanings, though if one were to refer to "The Rokkr" they would need to use a plural form of the word if they are using it to refer to multiple beings - that would be Rokkir (as in Vaettir is the plural of Vaettr).
In the story of Ragnarok, there is a "new pantheon" that takes place of the original one, where Baldr and other dead Gods return from Helheimr and Vidarr takes his father's role as chief among the Aesir and that "new pantheon" has nothing to do with the Rokkir. Most of the Rokkir in the story end up dead, if they're mentioned at all. "Why worship deities that will die?", some ask. The same question can be asked of those who worship Thor, Freyr, and even Odinn.
The answer is that it doesn't matter what the stories tell in terms of what will literally happen. Much like the Christian bible is not considered to be physically literal by many, the Eddas aren't regarded as literally and physically taking place in our plane. Whether it is an event that has happened, is happening, or has yet to happen spiritually (again, not physically), or if the events told are nothing more than metaphors for lessons to be learned is a matter of personal belief. The point here is that the Rokkir are not revered for their role in "end times" because Rokkatru is not a rebuttle of Asatru, like many try to treat it (and is where most of the controversy and misunderstandings come to play).
My religion may have started with Abey Helasdottir, but she defines it no more or less than I do because I simply choose to understand the Rokkir through personal experience and interpretation of sources representing them. I do not treat Rokkatru as Asatru with different flavoring because my Gods were not traditionally worshipped and I don't have the desire to worship them in a manner that folk worshipped other Gods - my path is one of reconstructing and piecing together sources that acknowledge all of Heathenry and what is associated, though I only partake in what applies to me.
And now to address the Gods listed...
Angrboda - Calling her the Mother Goddess is a gross misunderstanding of her role and temperament. She is first and foremost a giant of the Ironwood, a being worth her own merit before she is associated with others. She's also not the "hug you and kiss your booboo" kind of mother and treating her like that is often considered a sure fire way to earn her ire if she cares about your attempt to reach out to her in such a manner in the first place.
She is regarded as the mother of Fenris-Ulfr, Jormungandr, and Hela by Loki, though she is not defined as His wife in the lore and is also not considered to be a consort in shared gnosis - rather Loki was Her consort in the matter. She is also thought to be a possible mother to Skoll and Hati through Fenris-Ulfr (their listed father). As such, she is at times called the Mother of Wolves and is considered the matron of the Wolves of the Ironwood (or Jarnvidr, depending on if you use the English or Old Icelandic or Old Norse term); even in this, she is not defined as being their mother as an afterthought because she is seen more as their leader and who they answer to.
Loki - His association with fire is not a historical one because there was conflation between Loki and Loge in a poem where they were in an eating contest looked over by Utgarda-Loki (who, for clarification's sake, is not the same as either of the aforementioned). Loki ate his food quickly and wholely, though was surprised when Loge had consumed not only all of his food, but his plate and part of the table as well. At the end of the three contests, it is shown that Utgarda-Loki was using glamor to disguise his contendors - Loge, among them, was literal fire.
Loki is the son of Laufey (Leaf Island in English) and Farbauti (considered Cruel Striker). From the name of His parents, some have garnered the idea that Farbauti is lightning that "struck" Laufey and produced fire. This is an interpretation that is personal to several people, though it is still personal gnosis. Loki's bloodline isn't acknolwedged beyond his parents and brothers, so it is never mentioned whether he originated from fire giants or ice giants.
Now to address his Trickster status... Loki always cleans up His own messes, whether by prompt or by His own decision. He is considered one of the more playful deities, though He is so much more than that, just as Angrboda is more than a "Mother Goddess." To acknowledge only one facet denies the others and one only gets a piece of the big picture - this is actually one of His facets, as he is regarded as the Teller of Harsh Truths (for his role in Lokasenna). He calls out the aspects the others hide. He does so in a controversial manner, but often in a manner that needed to happen. As Personified works with and worships Him more closely than I, she can expand on who He is more in-depth.
Fenris-Ulfr - Marsh Dwelling Wolf, in English. The first thing to know about any Jotunn is that they are natural shape-shifters. Fenrir is considered a wolf because that is the state he resides most in; it's not that he's literally a wolf, even though his sons are also regarded as having wolf-forms.
Fenris-Ulfs role as a deity is more about His experiences than what he is. My personal experience with Him involved what I call Ulfgangr, or Wolf-Gait, which is akin to Berserkergangr (which involved bear pelts). In this experience, I shed what it was to be human mentally and beneath it was nothing but raw predator. You see, the Gangr state is an altered state of consciousness; it differs from other ASCs in that it physically alters the body by pumping adrenaline in basic terms. To assume the predator for me was a state gradually achieved by immense and deeply-seeded anger, egged on by the Hrimthursar (rime thurses/giants) "pulling" my human shell of a mentality into the ground. It put a strain on my body, so the bright light of the sun on the snow was harsher as I staggered and swayed forward. Towards the end of the experience, I had a mental vision of a wolf snout coming out of the darkness, and I acknowledged it as belonging to Fenris-Ulfr. I felt that he had orchastrated that experience.
I crashed afterwards and it had been not only an ordeal of anger, acknowledging the predator, and physical strain, but it was emotionally more than that. I felt the rage, the torment, the lashing out in fear. Fenris-Ulfr, like many of the Norse Gods, has very human traits and responses to different situations. It is often regarded that Fenris-Ulfr and Tyr have a complicated relationship because Tyr was the only one of the Aesir, even among Odinn and Thor, who stepped forward to place His hand in Fenris-Ulfs mouth when he was bound with Gleipnir. This was an act both of honor and betrayal, as Tyr is regarded in personal gnosis as having been close with Fenrir beforehand.
It was this act that others felt needed to be done, where a parental figure turned on the "child," that still spurns Fenris-Ulfr (even as Tyr is not Fenris-Ulfs father). It is for this reason I felt He reached out to me as I felt the same kinds of emotions from similar experiences. More than anyone, Fenris-Ulfr is more regarded by His relations with others because of how others' actions have affected Him. It is through this that Fenrir can be understood and connected with, even if He may not always regard those who reach out to Him; many do so for help in Shadow Self Work in dealing with their anger.
Surtr - He's more than just a fire giant - he's the leader of Muspelheimr, home of the fire giants. He is regarded as having been around since before the collision of Muspelheimr and Niflheimr, the realms of fire and ice, respectively. He is also one of those who is told as surviving the events of Ragnarok and otherise holds no grudge that is recorded. In this, Surtr appears to have removed any desire to care beyond that which He regards as worthy of being cared about. Many Jotnar are regrded as sharing this disposition towards life, though it manifests differently for each individual.
I've only had one personal experience with Him and He felt welcoming, if a little gruff. There are others who have more experience with Him that might better speak of Him. I can only speak that which speaks to me of Surtr, like his capability to rise to the occasion and recognize when matters have settled, opting not to perpetuate behaviors beyond what is necessary. For that, I feel he doesn't hold grudges in much the same way that a fire cannot ever exist in the same state as it does in any other point in time.
Jormungandr - my main man, right here. The first thing to note about Jormungandr is that it is not His name, rather His title (as is the case with many in Norse lore). The very second thing to note is that Jormungandr doesn't have a listed gender, and in Rokkatru circles, can be seen as male, female, or simply being beyond gender (all, neither, however you choose to interpret it). As one can see, I personally experience Jormungandr as male.
Beyond his initial introduction, He is mentioned three times, all in relation to the As deity, Thor. His first appearance is His introduction with Fenris-Ulfr and Hela; Hela ends up the ruler of Helheimr and overseer of the dead who dwell there, Fenris-Ulfr stayed in Asgardr, and Odinn is regarded as throwing the middle child into the depths of the oceans of Midgardr, earning him the title of Midgard Serpent. When He is mentioned along with Thor, He latches onto an ox head (which was a common sacrifice religiously) and Thor's companion has to sever the line to prevent disaster. The second time, His tail is disguised by Utgarda-Loki in Jotunheimr as a cat's paw in a contest of strength. The third time, Jormungandr rises from the oceans to spew venom in the form of clouds and then takes to battle with Thor (though his venom is erroneously described as poison).
And yet... Jormungandr isn't a God of any of these things. Here we can begin noticing a theme that just because certain Vaettr (in English, entity - literally anything/one with a consciousness) is associated with something doesn't mean that is all they are. So what is Jormungandr a deity of, if not anything based on lore? Here we see that the Rokkir are about how people connect with them more than they are about "darker aspects" - Jormungandr is often regarded as a deity of liminality, the in-between state of transition. This idea was not something I came up with, but one I recognized as being true personally speaking as I feel Jormungandr can be associated with Pathwalking (as he is regarded in the oceans of Midgardr as well as Jotunheimr) and helping to connect with other people and our surroundings in a manner we might not have otherwise. I also personally feel He wouldn't be against a transgendered person worshipping Him because of the matter surrounding His gender and the fact that a key factor in worshipping him is transition, even if this is not a thing every worshipper of Jormungandr identifies Him as.
I associate him with the color green, with fire/heat, with deep sea creatures, and connecting with people, though it is only through my connection with Jormungandr that I even came to these associations. On a personal level, I feel Jormungandr has the temperemant of His father than His mother; on the outside, he appears to me as if he should be scary, though His personality leads one to realize that there is more than initial impressions and pretense.
Hela - there seems to be some confusion as to her role in relation to death. Put simply, she is the overseer of the dead who reside in Helheimr (which is the part of Niflheimr she rules). She's not so much a deity of death as She is a deity of the dead - even those of Asatru revere her with honor as She's widely regarded by nearly everyone as someone not to be trifled with and someone who should be respected.
Personally She is the most solemn of the Vaettir that I have met, though less in a sterotypical manner and more that She takes her role and her word very seriously. Others have experienced Her in a more friendly manner than I have as I've experienced Her more steadfast nature - while Hela is a deity I worship, it is a more passive knowledge and set of behaviors to honor Her than actively working with Her. Yet again, others may expand on Hela better than I could.
Nidoggr - another Vaettr associated with death, though His role is regarded more as the consumption of rot and decay when He gnaws at one of the roots of Yggdrasil as well as when He feasts upon the corpses of thieves, murderers, and adulterers on the shores of Nastrond - the lake of serpents for the particularly nasty dead who lived less than honorable lives.
In this, He is worshipped as one who teaches us to recognize the necessity of the uglier sides of life and death, and how we should treat it as a part of the whole, rather than something to be disgusted at and ignored - He is another deity that is often associated with Shadow Self Work because Nidoggr forces us to face what we don't want to see and how we should address such matters, as ultimately letting wounds fester would destroy us more than the odeal it would take to overcome them. Some honor Him by picking up trash locally while others honor Him by taking care of the corpses of small animals and collecting bones and/or pelts; this is called Vulture Culture and can involve taxidermy for those who are into that and if one is going to get into it, I would suggest looking up the local laws about what is legal to own and what is not.
If one were to look at what Nidoggr can teach us in everyday life, one of those lessons could be about moving on from situations that keep us stuck in a rut. As with Surtr mentioned above, the lesson here is to only deal with what is necesssary or worthy of being dealt with, and then adapting according to the needs and desires that arise, which may not always be what we intend or expect them to be.
The overarching theme in all of this is that Rokkatru is different to everyone who ascribes to it. Personified is the closest person to having the same religion as I do, and even we have differences in who and how we worship, what we practice, and even how we learn. There are enough similarities that we can properly communicate and understand concepts, though it is as much a personal journey for us as individuals as it is a religion we and others share.
It is not enough to perpetuate the same information over and over again as you have done. This is literally just a copy and paste of the information given on the website and that is a disservice to a religion that is based on forging a new understanding even as we pull on traditional sources for our initial understandings.
If you are to pursue Rokkatru, I implore you to explore each facet of everything mentioned in the religions. Look for sources beyond what calls itself Rokkatru, look to different interpretations all across the board and begin to see the patterns form in your head as you figure out your own understanding and what is important to you. Because ultimately? This applies to everything in religion, magical practice, spirituality, and occultism - going so far as to extend to applying to all aspects of life, as that is what this religion is about. It is forging one's place in life through our actions, our understanding, and our personal development in relation to the rest of the world as well as in ourselves.