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