1) To get to the upper areas of Darkhold, you need a key, the issue with this is that it means people without the key cannot get there unless someone with 2 keys barters them one. I'd suggest removing that restriction and instead having doors needing a key be added at the appropriate doorways (I think the temple of Bane already has this, but the dungeons do not, and there's an unused doorfarme right by the stairs). This would massively simplify any form of RP that doesn't involve Zhentarim with a key to Darkhold.
2)
This couch is bugged, the PC's do not sit on it, but rather on the edge, or where the dialog box pop up3)
The doorway to the right (without a door) can be interacted with, but it sends you outside of Darkhold walls and you remain stuck there4)
This room here is unused, I recommend removing the pillar, adding some fancy glyph on the ground, a guard, adding a doorway (and a door that requires a Darkhold Key, too) and making the room able to be teleported in.5)
This door needs a fix in that once it is unlocked (requiring a Darkhol key) it remains unlocked until a reset or a crashThat's it