Yeah, Maerwald was pretty terrible.
I highly doubt he was written by MCA. In fact, I highly doubt anything in this game was written by MCA, and it shows as hell, especially nearing the end. And I can't wrap my head around why the fuck would they ever think about benching MCA for their "flagship" title.
You can most definitely tell that a LOT of Durance and GM was written by Avellone, good or bad. For example, Durance's dialogue has a *lot* of nodes that just repeat the others but in different wording, a trait Avellone seems to have developed for some his later offerings. You can tell by the way the dialogues are set up, how certain nodes lead into one another.
And Maerwald was excellent, and well-voiced to boot.