So I did the library quest in Pool of Radiance and I used a restoration scroll on her to get at least one level back. But now when I try to memorise spells with her it shows that she can memorise 25 level 2 spells but it's apparently way more than that, and after a while the whole spell list glitches out and shows shit like Burning Hands.

I tried to fix that by removing her from the party and bringing her back in, but it crashed my game.

I had this thought several times: I should save in multiple slots. Cause this is what happens.


EDIT:

I tried again, and this time I removed her from the party without crashing. But after bringing her back she's still glitched.


I really don't want to start over for the third time after getting fucked in the ass by the game...

Your character was probably drained more than one level and was not restored properly, which things to mess up things in PoR.
The Gold Box Companion may be able to fix the character.