Here is the full list of all 51 The Book of Unwritten Tales 2 achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Free the school of kobolds
Read all student files
Escape the Elfburrow
Be enlightened five times
Find out that Ivo is pregnant
Receive the hat of the Master Fisher
Finish the tutorial
Survive the fall
Master your first day of school
Finish the cleaning tasks of the headmaster
Make the library reappear
Solve the time travel side-quest
Get Nate sobered up
Hit all the symbols in the Drunken Punch minigame
Steal the lamp and flee
Receive the key to the city gate
Build your own golem
Mix the magic ink
Ask the right math problem at the first go
Animate your golem
Escape despite the surprising twist
Restore the electricity
Strengthen a friendship
Bring back a friend
Disguise convincingly
Help the zombies with the slate production
Rescue Ivo
Illuminate the dark cave
Solve the tasks of all four gods
Issue all four laws
Free your leader and your noble steed
Find Rémi and learn more about Wilburs staff
Fulfill the oracle's wishes
Free your team mates
Obtain the Spark of Life
Obtain the Red Pirate's compass
Obtain the Book of the Dead
Win the Nim game without cheating
Win the battle, but not the war
Get seriously lost in the Darkwood
Obtain the ghost detecting device
Chase off the spider in the Darkwood
Beat the Fear
Turn Timmy back to normal
Invoke the arch mage
Return unscathed from the castle
Prevail against evil
Watch the entire end credits