I don’t think that they would manage to get Eiri to work right now. With aizawa as he is right now, him being her primary caretaker either she uses up her stored “juice” for him, or we’ll get another walking disaster over there. Did her power work on mater or only living beings?
Eiri power are strange to me, like she’s capable of “un-birthing “ people, but overhaul referred to it as devolving, like the quirk bullets, but it makes me think that the quirk bullets have some kind of substance that gets eiri ‘s activated quirk cells into the target quirk cells, and this is the part that contradicts the text, returns them to their child or unborn state. If returned to child, then maybe in time, like years, the quirk would evolve again, but If it is to unborn, then there is nothing there, just like if mr compress reduced your stomach to a capsule, gone for good as there should not be something there to return.
We’d need to see how her quirk interacts with a missing limb.
Like certain virus right now, that knows how to find the cell that should infect by <virus and="" proteins="">stuff, the quirk biological factor might have something unique like that, that would allow a substance to find it through the blood.</virus>