Here is the full list of all 9 Cat Quest II achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Completed the Main Quest!
Completed all 67 side quests!
Obtained all 101 equipment!
Obtained all 12 spells!
Cleared all 73 dungeons!
Reached level 99!
Unlocked 3 Royal Arts!
Entered the new continent!
Completed the first quest!