Here is the full list of all 25 Chants of Sennaar achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
See the captured monster in the Laboratories
Meet Bards in the Library
Take a trip in the Alchemists' cable car
Attend the Bards' show in the Fortress
Meet a Serf in the Abbey
See the Great Door of the Abbey open
Finish the game (or not?)
Leave the Armory with the wrong disguise once the Call is made
Ring the Abbey bell three times
Reaching the real end of the game
Rebuild all links in the game
Rebuild half of the links
Visit the revived Abbey Garden
Rebuild a first link
Validate all glyphs in the game
Reach Exile
Activate all Terminals
Reach the Galleries
Validate half of the game's glyphs
Reach the Garden
Winning at both games in the Gardens
Reach the Frontier
Discover the Preacher's corpse
Reach the Abbey
Fill in the Journal's first page