Crowley didn't use the wrong calls, but did use Golden Dawn style pronunciation, which is not the original form of pronunciation employed by Dee and Kelley. I don't think Crowley obtained averse results from using the language incorrectly, but rather leaping before he could jump so to speak.
He covered the aethyrs in a very short space of time, and in my opinion, should not have done so that quickly. Most people use the Golden Dawn style pronunciation these days, I personally have had good results from it, however, I utilise the original guidelines and use the original letter forms of Dee and Kelley as I have access to better sources now.
Most Enochian scripts you find are reformed Golden Dawn ones which actually look a little different than the original letters. We have a lot to thank the Golden Dawn for in terms of Enochian magic, however, I feel as though there are some things which need rectifying and the language is one of them.