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