Here is the full list of all 17 Ys I Chronicles+ achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Complete Ys I on any difficulty.
Receive a free Talwar prior to entering the tower.
Completely fill the character notebook.
Unlock all details for all non-boss bestiary entries.
Complete Ys I on Nightmare difficulty.
Complete Ys I Time Attack.
Receive a free Short Sword.
Drive a hard bargain with Pim.
Confuse and astound the townsfolk.
Level-up Feena.
"Measure" Feena.
"Measure" Feena in the creepiest way possible.
Rescue Luta Gemma from monsters in the field.
Listen to Reah recite her poem.
Make Dogi break through three different walls.
Max out your money.
Master every achievement in Ys I.