From what I read, Avellone's work is limited to the module that is only available to Royal Edition or better. I'm not sure how much he is involved in the Kingmaker campaign.
Correct me if I'm wrong.
No, I wrote for the core game (and edited for the core game, although not every character - there was too many in the time provided).
I'm sure there's a link to a post here on the forums where I break down what I worked on, but in short, I only worked on part of the game - Owlcat, obviously, did most of the writing, and we had at least 2 other editors at any one time helping with the English translations as well (when I say "editing," it was less about removing words vs. naturalizing the English).
Paizo wanted changes on the module, so it's undergoing revisions (their revision requests were about 16 pages for a 32 page module, so it's taking a while to go through all their feedback).