From what I saw, patch 1.9 is quite important. Will it be introduced to GoG version?
I'm looking at a forum thread over on Steam where a dev claims that they've pushed a newer build to GoG. According to Adalia Fundamentals, there's still no changelog for the game.
I'm not sure changelogs are really mandatory on the GoG side, so I'm not certain whether the lack of changelog is definitive regarding a lack of a post-release update.
I take it you own the game. Can you check and report back? The game looks very good, assuming it's ever patched.