Javert's mother is specifically the often forgotten "healer" and generally magical incarnation of the character who hasn't had much presence in the mainstream. She's from the really, really old stories, back when the Welsh and French were in charge of the mythos. She's all the same person NOW because her primary characterization combines different people into one role (Madame Giry and the Daroga, anyone?), which Javert here gripes. The multiple and conflicting characterizations between sources being why she's so... extreme... and why there's no credit for her.
Incidentally, James is apologizing because although a lot of the more famous material is actually French, Arthurian legend is generally considered to be English, and many of the later English versions continue to support the "evil Morgan" characterization.
Keep this in mind. Characterization may come back to haunt them later...
Yes, Erik's little mental thought process is 1+1=Fish.
Erik belongs to Leroux and Webber.
Jareth belongs to Henson, Lucas, and Bowie.
Norrington belongs to Disney, Bruckheimer, and Davenport.
Javert belongs to Hugo, Boublil, Schonberg, and Kretzmer.