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