I was waiting for the Nalia abduction quest to kick in but it just didn't. when I checked the log I have De'Arnise keep is cleared but the De'Arnise keep has been invaded was still unfinished.

As I have been doing the game mostly solo so Nalia was not with me when I completed the mission, so I had to take her back around the keep to try and kick off the next phase (even though everyone in the palisade acknowledges the keep is finished they remain there). So I took her to see her servant which added another entry, whcih signalled to go to the cellar, but nothing kicked in there so I went to leave and then decided to talk to her, which kicked off the Torgal is dead dialogue and I got the Torgal dead soon all the troll and yuan-ti will flea. But I don't know what to do next, I've tried raising and lowering the drawbridge again, I've tried coming in and out of the secret passageway, I tried forcing talk again and speaking with everyone in the palisade... nothing.

Any help?

This is Nalia's personal quest, not yours. This is her home, not yours. She must be with you for this quest to complete satisfactorily. If you want to solo the game, don't take on personal quests.

Actually it turns out the correct answer was C:CreateCreature("naliames")

That's not an answer, that's a hack. You claimed the quest was broken. It is not.