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!
Obtained all 101 equipment!
Cleared all 73 dungeons!
Completed all 67 side quests!
Reached level 99!
Obtained all 12 spells!
Unlocked 3 Royal Arts!
Entered the new continent!
Completed the first quest!