Here is the full list of all 28 AereA achievements.
Retrieve the Baton
Retrieve the Drum
Retrieve the Violin
Use a skill 100 times or more
Collect all shop books
Hold 25.000 Clefines in your inventory
Complete all sidequests
Retrieve the Bell
Reach level 30 with any class
Reach level 50 with any class
Retrieve the Sousaphone
Retrieve the Accordion
Hold 10.000 Clefines in your inventory
Retrieve the Lyre
Retrieve the Harp
Complete 50% of all sidequests
Reach level 10 with any class
Poison an enemy
Burn an enemy
Freeze an enemy
Hold 5.000 Clefines in your inventory
Complete the prologue
Retrieve the Bagpipes
Complete a sidequest
Buy all skills from all classes
Upgrade all skills from all classes to level 3
Play with 2-4 players
Revive a party member