As mentioned in another thread, I think there's something to the fact the Enigmatic Maiden is just a couple synonyms away from 'Mysterious Girl', which is a title used for two different characters in Final Fantasy before, from FFIX and FFIV: After Years (well, one character and one collection of characters but we'll give it to them). And as it happens, both of those characters are artificial humans created by some greater villain with a plan to impersonate or replace a major party member.

I doubt she's an exact one-to-one of that whole framework--for one, she'd do an awful job at posing as any of our party--but I suspect that we're not looking at coincidence here.