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