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