It should be pretty obvious that the language is going to be Japanese because it's basically been established that he hasn't been cast into another world, but the far future. This isn't an isekai story, but a time travel story.
Hmmm ... my bet is that they unlock the deeply jealous god JUST before she eats the other waifus which somehow alerts the witch who will instantly return for the final fight. Either that or she eats all the other waifus from the first town then moves on to the sea village where she eats all the waifus there as well. SHE did just eat several people in a very short span of time so a couple of waifus might just hit the spot.
This part feels very dragged out. I don't know how it would be possible for that little cunt to eat so many people in such a short time and is she just a skin sack that covers some super energy dense body where every piece of girl meat turns into energy as soon as it hits her stomach?