https://magic.wizards.com/en/news/feature/final-fantasy-set-design-melodies-of-life
1.The Crystal's Chosen was called the Onion Knights. Since the designer kept asking what onion knight was the added the games number at bottom of the card.
2.Balthier and Fran were intended to be in the main set but as separate cards. Due to always being requested together they decided to put them together on the same card.
3.Ancient Adamantoise was going to be part of a cycle of bosses but they decided it's damage effect already made it unique enough.
4.Fang and Vanille were shifted down to uncommon.
5.While making the set Final Fantasy 16 came out.