I already gave Myrrhin 3 of the grimoires before I read this info 🤦🏻‍♀️ Good thing I'm doing another playthrough on the normal difficulty so I can get that last achievement on Steam.

Wanted to mention there's a back entrance to the boudoir. It's out of the northeast outer balcony, a few jumps along some rocks, and into the balcony off the boudoir, just a few jumps along some rocks. No invitation required. There's a note titled "Security Breach" in one of the inner balconies that mentions this being a way inside.