In line with Sol's thought, I believe much of the Enochian language is derived simply from Dee and Kelly's interpretation of what was provided to them from the spirits that they summoned. Indeed, in exploring the history of the language and their own methodology you find that there are occasionally inconsistencies within the language itself, and the words that they define.
However, in any such matter you may find inconsistencies as well. English is full of them.
At the core of it is an exploration of the Hermetic/Qabalistic concept of the Book of Life, or what some might also refer to as Akashic Records, or any such concept where there is a resource of knowledge telling of everything from the beginning of time to the end. It is generally explored in a process akin to the exploration of the hebrew tree of life, as most closely explored within the Hermetic versions of its study.
Angelic Language, by Aaron Leitch provides a rather extensive history and study of the Enochian language and tradition. It is a two volume set that describes the history and lore of Enochian tradition in the first book and details the language within the second book. Last I looked, this site sold it.