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.
Speak to all of the spirit animals.
Find the statue of the fox.
Find the chiseled stone map.
Step into the well.
Find the giant birdshrine.
Find the ancient battlefield.
Find the bones of an old beast.
Find the statue of crane.
Find the statue of the deer.
Find the Crab Island.
Get some Lambaby love.
Find the Ancient Llamba.
Completed the game.
Complete the Monastery.
Discover all areas of the map.
Find the dwellings of the rift cult.
Find Erin when she's gone.
Complete the Archives.
Complete the Eventide Sanctuary.
Escape the collapsing cave.