Here is the full list of all 30 Squish and the Corrupted Crystal achievements.
Found the alternate exit in Hidden Hollow.
Found the second alternate exit in Grasslands.
Found the first alternate exit in Woodlands.
Found the second alternate exit in Woodlands
Found the third alternate exit in Woodlands.
Found the alternate exit in Canyon.
Found the first alternate exit in Cloud Sea.
Found the second alternate exit in Cloud Sea.
Found the alternate exit in Crystal Cavern.
Completed the first level.
Completed Grasslands
Completed Woodlands
Completed Canyon
Completed Crystal Core
Freed Maji from the corruption
Freed Mwiba from the corruption
Freed Upepo from the corruption
Freed Ulizini from the corruption
Completed Clould Sea
Died at least 100 times
Completed a level in 12 seconds or less
Collected your first token
Earned 100% completion
Collected all the crystals in a level
Collected every crystal in every level
Found all hidden exits
Completed a level with gold time
Ascended to the top of the tree trunk in Diacris
Earned gold time in every level
Collected every token