Headscratchers / Black Clover

• How could Elf Fana use the same magic and Grimoire as Human Fana. Both Liar and Vetto seem to be using their old elf magic and presumably Patry too because they made a point he couldn't use William's Grimoire. But how is Elf Fana able to use Fana Grimoire?
  • Maybe they have similar magic types?
  • It certainly makes the most sense that they are able to share Grimoires because of having the same magic type. Drowa and Eclat are shown using Mirror and Eye magic much like Gauche and Marie do, which probably wouldn't be possible if they had different types. Patri not being able to use William's Grimoire is as simple as his affinity being Light Magic when William's is World Tree. He just got unlucky with being revived in someone who had a different attribute than him.
• Did the reincarnation spell inject random people with Elf souls or was it something more? Because it's an extraordinary coincidence that nearly every elf was identical to the person they were possessing aside from having white hair and pointed ears. Barring Patry, they all had the same magical attributes as well. It wasn't as if the Elves were literally reincarnated into these people, or else the Elves wouldn't have had separate souls. It's possible we're operating under different rules than in other media re: reincarnation, but it seems really ambiguous.
  • A common mistake is to believe that the reincarnation spell was cast by Patry once the magic stones were collected, but it was in fact cast centuries ago, when the elves where all killed. Some people having the exact same faces as the elves of old at the time of the story isn't a random twist of fate, it's the result of the reincarnation spell and Patri using the stones only awaken the elves' souls lying dormant in their reincarnation.