Nothing changed on Larian's side regarding how the game is uploaded to GOG between DOS2 Classic and the Definitive Edition (I've asked the people that perform the game uploads). As I mentioned before, there is unfortunately nothing Larian can do about this situation.
I'm glad you got a quick answer from GOG. I contacted them Friday two weeks ago about this (as a customer that got DOS2 by backing it on Kickstarter and redeeming it here) and still haven't gotten a reply (other than the automatic confirmation that they got my support request).
Well, ithe french support is faster then years ago (when there was only the one based in Poland)
Since you're in Belgium i have no idea if the support is the same as mine.
I got an update, and frankly, that was almost expected :
It's GOG's fault
(ugh again !!!)!, dues to technical issue, however the reason aside it's a technical one, wasn't given (i'm not even sure the support has more knowledge than that...). Well GOG continues to be equal at itself ...sigh.
So to sum up, we could expect an offline patch, but when ? (that's the question), and i wonder if in the future for this game, the issue will continue or not (i hope not).
Personally i could play another game, but for others who can't...
IIRC Larian takes much more longer to answer.