In the absence of evidence to the contrary, I'm taking the "single mutable timeline, achronal soul" interpretation of time travel. There isn't a leftover timeline with a vanished witch, the world is properly wound back. To remove the identity issue, a soul is a transcendent thing existing beyond time and assert their return into the world once appropriate. Even if they can't consciously remember, they are still the same person.
And no one can say I'm wrong, because nothing specifically details how time travel works in this setting. I'm picking the ones that make this the happy ending it is supposed to be.