Here is the full list of all 52 Letter Quest: Grimm's Journey achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
Swap all letters 50 times
Earn 40 crystal stars
Earn 120 stars
Purchase 50 merchant items in battle
Earn 20 crystal stars
Earn 99 stars
Spell 2000 words
Fill the entire board with duplicator tiles
Fill the entire board with plague tiles
Do 100 critical attacks
Fail to open 20 treasure chests
Bust apart 100 gem piles.
Purchase 30 upgrades
Defeat 250 monsters
Use 2500 vowels
Spell 200 double-letter words (ex: 'bubble')
Purchase 10 potions
Dodge 50 attacks
Defeat 5 monsters with exact damage
Complete 50 quests
Use 5000 letters
Spend 25000 gems
Spell 25 palindromes
Purchase 5 books
Reach max level with one book
Open a treasure chest with no incorrect guesses
Use 100 crystals
Use 25 plague tiles
Spell 5 eight-letter words
Lose from taking tile damage
Earn 1000 book XP
Earn 15000 gems
Deal 25000 damage
Spell the word BACON
Spell 50 six-letter words
Spell a word that contains two 'Y's
Spell the word BANDITS
Open 10 treasure chests
Use 500 corner letters
Spell 3 words with no vowels
Use an entire row in one word 3 times
Take 10000 damage
Use 500 letters from the top row
Earn 29 stars
Deal 10000 damage
Spell 10 seven-letter words
Spell a word that does zero damage
Finish a stage with full health
Spell a word containing two or more crystals
Leave a monster with only one health
Beat a stage with only 1 health remaining
Spell 3000 words