Here is the full list of all 22 Ever Seen A Cat? 2 achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Cleared the beach for the first time.
Cleared the cafe for the first time.
Cleared the gallery for the first time.
Cleared the icecream stand for the first time.
Cleared the recreation room for the first time.
Cleared the cottage for the first time.
Cleared the greenhouse for the first time.
Cleared the house for the first time.
Cleared the amusement park for the first time.
Find all the individual cats at the beach at least once.
Find all the individual cats in the cafe at least once.
Find all the individual cats in the art gallery at least once.
Find all the individual cats at the icecream stand at least once.
Find all the individual cats in the recreation room at least once.
Find all the individual cats in the cottage at least once.
Find all the individual cats in the greenhouse at least once.
Find all the individual cats in the house at least once.
Find all the individual cats in the amusement park at least once.
Find 100 cats from any place.
Find 500 cats from any place.
Find 1000 cats from any place.
Got all the achievements!