“the administrator”… white mask wonder crumbs?
(joking, joking. unless…?)
(Referring to the v5.1.2 synopsis here, I believe)
Heh, well, we don't know who they really are, just that they take the form of Merope while in Wonder World and seem to have some knowledge of how the place works, so it's not impossible!
On that note, since I haven't had a good chance to note it anywhere else, when Wonder asks them for an actual name, the Administrator does eventually give him "普洛薇" (pu luo wei), which seems to be a play on Merope (which is 梅洛普 (mei luo pu) in Chinese; note that the second character is the same in both names, and the third character in Merope is the first in the Administrator's name). Meanwhile, the Japanese pronunciation in the audio sounds like "Purobi", I think.
I haven't been able to find any useful results when trying to search that Chinese name (unlike names of, say, Personas, which will usually get me the Chinese Wikipedia page for that figure), so there's no hint there, either. Given the apparent joke (Merope backwards, with a W instead of an M), it's possible something like Perowe or even Eporew would be the more accurate English translation, though Probi or Provi or something might match the Japanese dialogue better.
I might just keep calling them "the Administrator", since that's easier and matches the words used in both Chinese and Japanese? The official v5.1.2 synopsis still referred to them as such, although I think the game usually uses their name instead.