Praise on you !
Whatever little thorough playtesting I did was to make sure that I remembered correctly the things which bugged me in my first playthrough, so I wouldn't unnecessarily and incorrectly say "oh, this sucks doesn't work". Niara did a pretty thorough analysis of spells and statuses, but is now focused on animation for short races.
It's good to have people pushing the code/logic/variables/flags for the permutations in how the story plays out, to see where it breaks. This is important. We need more of these tests (from you, or other players, ... or Larian).
About 4), it could be justified that Dror Ragzlin has not yet heard of Minthara's death, some situations (really, some). Which raises an issue. There is a dissonance between level-design and immersion. On the one hand, the level design of fortress is such that combat in one room will usually not spill over and you won't have to fight the whole map in a single fight. On the other hand, from an immersion point of view, goblins don't routinely move from room to room, there is no time (you can go out and take a 1h short rest or a full night, after killing Minthara, before coming back for Dror Ragzlin, it won't change anything), and the sound of a fight doesn't echo through the halls, only sight matters.
Regardless, the party should be able to let know Dror Ragzlin that Minthara is no more (and that he is next).
