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