With regard to the Soujo's victims having no lives to return to, one thing to consider is how long the Soujo's have been active. Decades? Years? Months? Weeks?
Those girls who they took most recently may well have families and lives to go back to, and the younger the Soujos are, the greater a proportion of their victims that will be.
As far as rebuilding bodies, it occur to me some time ago that we may have an option here for help, if a highly controversial one:
Anri.
It's questionable whether she will agree to such a thing, and we'd have to find a time and a place to remove her antimagic and trust her in doing so (though frankly, if the antimagic interferes with magic channeling? I guarantee we're going to run into that problem
anyways,) but she may be willing help in rebuilding bodies and giving people a place to recover.
If we believe she can be trusted in that it's a chance for her to carry on helping people. She wished to be someone to carry on Yuuri's life, after all, and helping people as her friend once did may give her purpose. Beyond that, it's also practice: We have no guarantee our methods will bring back Asuka Yuuri's body, after all, and that is the one person she'd most like to help. And, of course, if clear seeds just need to be fed happy or resonant thoughts and experiences, her thoughts of giving other girls their lives again may well help Yuuri.
On a less controversial note: we can and should consider Fukushima's help, for both giving people a monitored place to recover and just plain
advice.
Tsuruna Yuki
did say she was an expert in crisis management, and this is certainly a kind of crisis.
I mean, Kyubey doesn't puppet people around, so our self-control enchantment probably does nothing. And the "invisible mind" enchantment only hides minds from being read - if Kyubey's method of altering memories doesn't require him to read minds, then it'll also do nothing.
So tl;dr, our current enchantments probably do nothing to QB.
I think we should finish testing our enchantments for real before making such assumptions, especially given our intentions in making them.
Remember: Our goal in making that enchantment wasn't for people to control their own bodies, it was to control their own
minds. And we
very specifically had a memory manipulator in mind when we did that. It's certainly possible we failed in our design, but hardly certain.