The reveal is like suddenly splashed with a bucket of cold water out of of nowhere.
It does bring up a possible interesting implication. The “homonculus” is trying to merge with itself by going back to the past, and that’s it. If Sildonia is right, when he is successful, he’ll just do it again. So who’s to say how many times he has done this before. It’s possible that he has been looping until Kail finally break it.
Consequentially, once he failed to loop whatever stack he has would’ve been lost (not that he cares) and instead Kail end up stacking with himself (once).
Anyway, the theory aside. The plot is interesting, but as other posters have written, the storytelling could be better and perhaps the author got burnt out.