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