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