I have tried it four times.
I cannot use Charm on her during any part of the scene.
Are you sure you were able to do that after freeing her? I keep getting a FAILED message.
That's including not using confuse, use confuse, bring her back to the room and use Charm from there.
Also, she's not a Willing Slave regardless. "Willing Slave" means that no magic is involved on the character in question.
The only thing that happens in the room is that there's no FAILED message.<ac_metadata title="In regards to the Val edit"> </ac_metadata>