I think this system is as developed as it needs to be to use it in my NWN2 adventure module, but there is one thing that only recently occurred to me to try that might make it that much more convenient to use. It's pretty convenient already, though, since I've gone through and made it all generalised to the point where you don't have to touch the scripts once you attach them to the appropriate location on your NPCs or objects.
Instead, you assign local variables to your placed instances, and modify them through conversations or by firing scripts on conditional actions, such as "On Enter", "On Inventory Disturbed", "On Death", etc. In other words, anything that triggers a journal update will just need to have this script fired too. Everything else is handled through local variables.
This way, you can also have one questgiver begin the quest, and a second questgiver finish it, which is very important for certain kinds of quests (like breadcrumb quests). Anyway, I've been documenting how to use it in detail.
The video also shows my modification of the dialogue panel from my HD UI mod.
I'm close to getting ready to start on the adventure module itself. I just want to play the game a little bit more first, but I'm really getting anxious to start.