Here is the full list of all 20 Legendary Mahjong 2 achievements.
Complete all levels in all the temples.
Undo 100 moves.
Restart 5 times.
Restore the Temple of Wisdom.
Restore all the temples.
Restore the Temple of Beauty.
Restore the Temple of Water.
Get the highest rank.
Restore the Temple of Time.
Restore the Temple of Fire.
Match 10000 tiles.
Use 10 Whirlwind Tiles.
Use 10 Magnet Tiles.
Unlock the Celestial Gate.
Restore the Temple of Earth.
Match 10 Lock Tiles.
Restore the Temple of Air.
Match 10 Ice Tiles.
Get a new rank.
Match the first 2 tiles.