Here is the full list of all 22 InfiniPicross achievements.
A Certain Familiarity
Use The Workshop
Change Theme
Create a Theme
100 Solved
50 Solved
25 Solved
10 Continues in a Row
10 Solved
5 Continues in a Row
5 Solved
One Continue
Reset a Filled Grid
5x5 or Bigger Completed
10x10 or Bigger Completed
15x15 or Bigger Completed
25x25 or Bigger Completed
50x50 or Bigger Completed
99x50 (or 50x99) or Bigger Completed
Set a Seed
First Solve
3x3 or Bigger Completed