Sometimes, achievements lists have to be scanned in after the game has been added to TSA. For Panzer Corps 2, the list is now there, and I did a full scan on your profile that scanned in the two achievements you got.
What is the 2nd game you mentioned?
Edit: if you come across any game on TSA that doesn't have the achievement list, you can report them here:
Games with missing achievementsFlippol checks that thread regularly in order to scan in the achievements lists.