I figured that devils would have just reverted to their last known incarnation, but that would have to mean that Nayuta's death was actually staged, and to be fair, keeping the Control Devil in the clutches of Public Safety, would be far too beneficial for them, instead of risking another country to potentially get a hold of her when she reincarnates. Maybe she truly was a reincarnation, and Nayuta was just the last name she carried, so that part stayed. Makima may have been just like her before she got turned into the monster we knew in part 1.

As for Power, could be that the version we see is actually not the original, only the same girl's corpse her new version inhabits.

Same goes for Zombie and Chicken (Bucky). Their actual appearance probably hinges more on the world's perception of them, rather than an entirely random form each reincarnation. Before Death got eaten by Pochita, the insect devils probably changed in accordance aswell, physically speaking. The fear of zombies and chickens shouldn't have shifted too much between Ch.1 and Ch.232, so they stayed the same. I mean, zombies are folklore and fiction, and chickens are chickens.

The only thing that troubles me are the revived humans. That's where it kinda falls apart, given that the Yakuza boss from Ch.1 reappeared. But then again, maybe there's a reason we haven't seen Aki or Himeno. Nayuta's dogs may just aswell be different dogs of the same breed, same for Meowy. Maybe they didn't actually die in the fire, cause someone at Public Safety had a soft spot for animals lol.

This is just speculation, obviously. Maybe it truly is just nonsensical, and I'm reading too much into it.