After completing the questline peacefully (Mardracht gave over the gem) taking the minor gate deposits the party outside the front gates and immediately starts a fight with the archers on the towers. It would be much better to delay that fight until the party approach the gate, and allow them to walk away otherwise. Leaving the keep by teleport should not send the party into a fight?
Anyway, I cleared the courtyard and found the other entrances to the ground floor level. This revealed a weird bug - every time I entered the keep my reputation with Scavengers and Masgarth rose. Quite by accident I did it three times and maxed out my rep with those factions, no idea why.
Finally it would be nice when picking up something that you're not supposed to pick up, to get some kind of warning you will start a fight. E.g. highlight it in red, or have the character warn the party to leave it alone. I got that with the Aksha (?) fight where I negotiated passage through to meet Mardracht but then had a crafty look at the +1 armour hanging there. I did not realise it would initiate combat :).