Here is the full list of all 20 Star Sky 3 achievements.
Friendship
They are precious
Being friendly
Fruit from the tree
The guardian
Grow more
Release it
Use it well
Water or not
She is watching
It is uncovered
A beautiful thing
Together forever
A trait passed on
Where they roam
Free at last
Dark turned to light
A magic gift
Path to the Waking World
They Meet at Last