Here is the full list of all 20 AER - there are Memories of Old achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Find Erin when she's gone.
Step into the well.
Find the statue of the deer.
Find the statue of the fox.
Find the giant birdshrine.
Find the chiseled stone map.
Speak to all of the spirit animals.
Find the dwellings of the rift cult.
Find the ancient battlefield.
Find the Crab Island.
Get some Lambaby love.
Completed the game.
Complete the Monastery.
Find the Ancient Llamba.
Complete the Eventide Sanctuary.
Complete the Archives.
Find the statue of crane.
Discover all areas of the map.
Find the bones of an old beast.
Escape the collapsing cave.