Here is the full list of all 21 Jusant achievements. It takes around 5-6 hours to unlock all of the achievements on Windows.
Read all of Bianca's journal entries.
Read all letters.
Listen to all shells.
Activate all frescos.
Complete all cairns.
Complete the game.
Use the echo on a frozen ballast in Chapter 6.
Warm up the ballast in chapter 6.
Turn all altars.
Restore your stamina more than 50 times while climbing.
Place a piton at the top of a wall run.
Complete more than 200 jumps or double jumps in one game.
Stop 25 pebbles with a single echo from the ballast.
Turn an altar.
Scare more than 10 chocos back to their burrow.
Activate a fresco.
Hug the ballast 20 times.
Hug the ballast.
Complete a cairn.
Listen to a shell.
Read a letter.