Had an idea about the travelers's fears if you are willing to hear me out about.
All "travelers" have the feeling of "it's over when you reach the end" but for different reasons.
For Sif, he has no home or memories to return to. Hence why Mal Du Pays takes the form of Siffrin in the game over screen.
For Bonnie, their relationship with Nille is in the gutter due to their last words and fear of not having her or anything to return to.
For Isabeua, who travels to find his idenity, and distance himself from his past, the party acts as his "rock" with fear of crumbling once it ends.
For Odile, who travels becuse of her mixed heritage, having a "family" she would do anything to keep safe yet never admit it her fears.
For Mirabelle, who struggles with her innability to "change", having stability and life injected thanks to the party yet anxious for it ending as with it over, she'll go back to her own quest to change with little effort. Just stuck in rot.
Anyways. Hope these ideas help! I've read more than a few other AU as well as the script itself, so these ideas are mainly more of a base. Adding new wrinkles or changing issues enough to make sense is fun. And the idea your SwapAUs all coming together for some ungodly reason to partaking in angst and time loop shenanigans is enjoyable to me.