Here is the full list of all 15 Ephemera achievements.
Earn 500 development XP.
Earn 1,000 development XP.
Earn 2,000 development XP.
Reach 3 maturity.
Reach 6 maturity.
Get into your parents' bedroom.
Reach 14 maximum energy in the first stage.
Reach 10 happiness while at school.
Discover 'it' at school.
Help Harry during stage 2.
Dig up a collectable.
Bake a meat pie.
Repair a bridge.
Win a fight.
Defeat the evil entity.