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