Is it possible that the Juju, being an aspect of the game is some sort of super powerful McGuffin that actually has different powers depending on the aspect of the player that touches it? I.E. John being a Wind player, gave him the ability to retcon or change history ala The Winds of Change?

There are several jujus.  The house was one, Lil’ Cal’s another, so are the lollipops that activated trickster mode, and pretty much every device used by the Felt are jujus as well.