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