I fixed her

she would be happy in the main hall of the throne room, she can be there for the eternity as she wanted

I petrified Disa, sincerely I wouldn't have bet this could be possible, I'm past the coronation, so her missing won't be noticed in the main story (I won't be able to evacuate Vernworth in UM I suppose). maybe it's because of this possibilities that before the Coronation you can't find her in her room.

I wonder if I can do the same to Phaesus