I seem to recall it being implied that the B2 session's incipisphere is in a different location in the Furthest Ring than the B1 incipisphere. If that's true - if the B1 incipisphere didn't simply BECOME the B2 incipisphere - then do we have any idea what's left of the B1 incipisphere now that the Scratch is complete?

It doesn’t exist anymore. The Scratch erased it all.