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