MarkoH01: The Wolf Among UsSylvanFae:
has ingame achievements and Galaxy achievements. It is funny since they obviously are handled seperately. I unlocked an acievement while the Gaalxy services were disabled (it was a test for a different thing). When I started Galaxy this unlocked achivement was not shown even though starting Galaxy automatically activates the services again. This also makes me wonder if this feature was added after TTG has closed or if it has been already in the old version as well. If the first is the case other TTG that came back to GOG could have ingame achievements as well...
I believe achievements that unlock stuff (nine parchments) are handled differently than regular list with achievements that are just listed in game like Trine 2.
But the TTG achievements are merely bookmarks. You finished chapter 1,2,3,4,5,6 - that'S all. So no unlocking here. Still they have two kind of achievements ingame and Galaxy.