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