1. Yes. FUCK yuri.
2. As ppl pointed out, it's only an issue when it overrides the premise, is used for stupid ass reason like an NTR/'rescue' situation, or when it's put on a pedestal the genre just doesn't deserve. The fact is, it's justvas irritating when other guys are involved. Ppl get territorial with harems they like, that's it. Yuri is a sour point precisely bc ppl have this idiotic tendency to wanna put it on a fucking pedestal.
3. The author loves trolling the fuck outta ppl with anyband every gag imaginable to the story, and that includes 'girl-on-girl is hot'. The author is pretty blatant that it's a self aware troll bc Hahari, the biggest degenerate in the series, gets off on it for us.... and is Hakari's mother.... leaving aside that consentual incest between adults, to the best of my knowledge, is actually legal in Japan (not that it matters. I honestly don't care. I ascribe t9 a very 'live and let live' philosophy on shit like that. I have a pretty complex and strict worldview though, mere opinionating excluded), Hahari's character honestly reminds me of RL degrnerates who aren't that different about their fetishes... only, y'know, way more exaggerated. Looking at her reminds me of actual ppl (like some of you lot). Can't help it.
4. I've already commented and given plenty of other harem stories where it wouldn't be unusual to see some yuri fanservice. There's A LOT of them, and it's fine since it never gets in the way of the story. Plus, Hakari and Karane were basically a couple after their first 3 way kiss anyway. The zombie kissing incident happened, and so ofc it'd go in that direction. It'd be weirder if they 'didn't' develop some level of attraction to each other.
All that matters is that Rentarou stays firmly at the center of their relationship, which he has. Like I said, the story wouldn't work without him and it's bc of him that the girls are much happuer... case in point, Hahari isn't in prison yet for unspeakable, non consent related criminal acts that we all know she'd commit if given half a chance...