Problem with unfinished quests

[Free Luigi M.]

So, I finally decided to play this game from GOG, since I quite enjoyed its predecessor. I am liking it so far, but it seems to be riddled with small bugs, or at least some oversights.
In particular I have two quests that I can't figure out how to complete, and I am suspecting they may be broken.

The most important one: "A Fate Worse Than Death". When I passed the gargoyle maze and met the three necromancers, I already had the souljars in my inventory. Nevermind telling them you had them right with you was not even an option (come on Larian, seriously?).
So I get into a fight with them and I kill them. Then they resurrect and I find myself in a fight again. I just dropped the three jars on the floor and destroyed them with a fireball. Which killed them for good.
And that's fine, but the quest isn't completed at all. Instead the most recent entry says I have heard of a vault that might contain some souljars and that I should check it out.
I have already been there, looted and destroyed those jars for Christ's sake! How can this quest be so badly coded? Is there any way to get it done?

Second one: "The Murderous Gheist". Ok, I got that Magister Yarrow is his daughter. Problem is that Yarrow attacked me on sight because I had just removed my party's collars and didn't realize that would make all the magisters immediately hostile. Not a big deal. I would have killed them anyways. But then I can't complete this quest, can I? I went back and killed the Gheist too, just for good measure. That still didn't close the quest. Come on! That's just ridiculous. Both the characters involved are dead! How much more closed than that can it get? There isn't even an option to tell him "Oh hey, by the way I killed your beloved daughter, how about that?".

This role-playing game is seriously lacking in dialogue options and doesn't account for obvious ways through which players might approach quests. That's some serious flaw. And I am guessing that if you don't complete these quests in one of the 2/3 ways the developers intended to, then they just break and you can't ever close them.

[Free Luigi M.]

If some mod can move this thread to the appropriate sub-forum, I would be grateful.