the ghost is located at the end of the right side of room 202. it can be seen using a UV flashlight. as for the inscription and why you couldn't find it, I'm sorry, but I don't know what to say because I haven't encountered anything like that myself.
actually i just found her in m202. i went to the hallway where it says "magic girl" used the uv light on it and then went to room F103 used the uv and it says "no face" then i went back to M202 and she appeared9 days ago(+1)
i figured out you couldnt use uv after the update, apparently you needed a dark mirror instead and then it would appear. it was a pain to find out, but I got it.