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
Together forever
She is watching
The guardian
Use it well
Dark turned to light
Release it
Grow more
Water or not
A trait passed on
Where they roam
Being friendly
Free at last
Fruit from the tree
Friendship
They are precious
A magic gift