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