Here is the full list of all 38 Castaway Paradise Complete Edition achievements.
Grow every type of flower
Grow every type of fruit
Donate all shells
Donated every collectable
Make a profit of 5000 gems on the Stock Market
Rebuild the Lighthouse
Grow every type of crop
Remove 25 cobwebs
Live the luxury life of a VIP
Rebuild Angus' Trailer
Make a profit of 2000 gems at the Bank
Rebuild Francis' Pirateshack
Make a profit of 500 gems on the Stock Market
Donate all fish
Read 50 chit chats
Rebuild Victoria's Mansion
Completed 100 quests
Harvest 50 crops
Donate 15 shells
Rebuild Amelia's Planehouse
Changed every piece of outfit
Unlocked a gate
Unlock the second room in your house
Donate all bugs
Collect 25 pieces of garbage
Donate 15 fish
Remove 50 weeds
Donate 15 bugs
Donate a collectable
Rebuild Harold's Museum
Rebuild Gustave's Bakery
Rebuild a bridge
Used every piece of equipment
Completed 25 quests
Remove 25 stones
Get your first collectable
Wore an outfit of the opposite gender
Completed the tutorial