Ah, I've found what you're referring to.
Curiously, I can't actually see the AI personalities in the Divinity Editor where you described them. When I open a dual dialogue in the editor I see the AI box but there's nothing listed in it, and when I click on it I see all of the personalities in the "available" section and not a single one in the "assigned" section. I have to open the dialogue files in a text editor to see which personalities are assigned to which dialogue options.
But I think that's probably just a problem on my end with how I set up the editor or the dependencies or something and I'll tinker with it all until it makes sense. Barring that I can just edit all of it in the text files directly.
Anyway, I think I see how this all works now. You've both been a great help, thanks a lot.