Some achievements in GOG version of OFDP2 are broken:

* "The wise amster wander the lands" - I've completed all levels on all maps and I didn't get this achievement, it seems it was always broken since according to GOG statistics no one ever unlocked this achievement
* "Enter the background music test" - didn't unlock for me even after I entered background music test few times
* "Beat the last level in the Gauntlet Normal" - didn't unlock for me when I finished the Gauntlet mode and unlocked blind version of it

I was able to get the "Enter the background music test" achievement: I opened the screen and played the music. I also see some players got the "Beat the last level in the Gauntlet Normal" (I was not able to beat the last level so far).

So from my point of view, the "The wise master wanders the lands" achievement is the only one which is broken in the GOG version.

I've got the regular gauntlet achievement after completing it the second time (blind gauntlet gave me its achievement after the first completion). Had to do the same dance with both bonus stages and the last level on the map.
It may sound silly - I've noticed that sometimes achievements don't pop right away, but after replaying some training level. So now every time I don't get the achievement right after fulfilling its requirements, I go to the training mode (or one of the pinball levels).
And yes - "Wise master wanders the land" won't unlock for me (despite completing 100% of all the maps and 20 pinball levels).