Here is the full list of all 15 Heart of Enya achievements.
Make soup for the first time
Use a Flame Move for the first time
Trap a Frost underneath an obstacle
You made a new friend
Get Soleil to open up
You found someone in the ice...
Get Raina to open up
Get Bapy to open up
The gang's all here!
Escape from Absolute Zero
Defeat Absolute Zero
Defeat the first boss without needing to retreat
Defeat all the Frost
Have a day where no Frost appear
Defeat the final boss without needing to retreat for the entire battle.