Nothing wrong at all.
It's difficult to say, many names are derived from the file names, which I have not gone through, so whether or not that NPC has one I can't say.
The only mention of her on this wiki that I could find is in the effects page of the ghost effect and she is only referred to as "ghost" within it.
So it's possible she has no file name of any note.
In any case, that's what I like about these games, there is very little definite canon, so much of it is up for the player to surmise.
For example, Smile is a file name, but was also mentioned to be 'oniisan', but the former became the prevalent name.
So if no theories exist of her, here at least (I don't know about elsewhere), do feel inclined to create your own.