Here's some more info. Can't say if those are bugs, but let's call them oddities.
- Viconia takes damage upon meeting her. Much later, she took damage from an unknown source again.
- the new area has a weird map. It's blank on some parts (only when you look at it from minimap - some areas, even if explored, show as black).
- when entering Cloakwood mines, my party got hit by Horror spell. Most of them failed the save and scattered, but the animation (whirling circles) remained where they got hit, even after the Panic effect was gone.
- battle vs Daveorn - he summoned about 60 monsters instantly, in addition to Guards and exploding skeletons. Cute, to say the least. I used a Pro Magic scroll here. The character I used it on was prohibited from using innates, potions etc. but only briefly. He was still protected from magic when he could use innates/potions etc. again.
- afaik, in vanilla game, Daveorn's chests are guarded by some kind of Slime, iirc it's worth 2k exp. It isn't there anymore.
- in BG, one can buy Ring of Invulnerability. Isn't the price slightly too cheap (750 gold) for it's effect - +2 AC, Minor Globe?