Great Beast split personality?

I am playing around with a concept. Could you review and indicate if anything is explicitly against RAW?

When an advanced Bjornaer goes Final Twilight, their animal side goes Great Beast, and their human side does not return from Twilight.

However, this can only happen after they have been initiated into the Heartbeast at the gathering of twelve years. Is the Bjornaer's soul mystially split before andafter initiation?
Could the bjornaer also leave behind a "ghost" of who they were from before initiation?

So while the Great Beast goes off, could there be, say, the ghost of a 16 year old apprentice haunting the Bjornaer's former Talisman? Or something similar

TMK at least the Bjornaer claim, that many or most people, Gifted and not, have a potential beast shape. Their control of it is just non-existant or incomplete: the intitiation gives them full awarenes and control.
The worst enemies of the Bjornaer are lycanthropes, shapeshifters with little or no control, but quite some power.
I expect the typical split to be between spirit (inhabiting the Great Beast) and soul (undergoing all associated with Final Twilight).

Most Bjornaer do not become Great Beasts. You need to be initiated into the Inner Heartbeast for that. Those who do not have the Inner Heartbeast will become mundane animals on Final Twilight.