I'm having a stretch of free time right now so I'm just cramming in so many otomes :x
Oh boy, if you weren't enthralled by Black Butterfly, then I feel like 7'scarlet is going to be a real slog. To be brutally honest, 7'scarlet feels like more of a mystery VN with romance shoehorned in and ends up not doing either of them super well. To be fair, the mystery aspect is kinda interesting and the last 2 routes start to kinda make up for things so could be worth getting on sale. I found the MC irritating since she was often so stupid and running headlong into clear danger. Anyway, suffice to say, playing Black Butterfly afterward was such a breath of fresh air to me in comparison. Aw, too bad you didn't really feel much for any of the BB characters, I enjoyed the two cinnamon roll characters. And I actually liked how they did the childhood friend/first love trope with Natsuki and acknowledged how (SPOILER if others are reading: even in the endings where he dies, that it's not that easy for the MC to just get over him since she did love him). Also, the yandere BB is definitely better than the one in 7'scarlet, no question. And I probably worded "The bad end is bad in a different way sadly" a little misleadingly, it's really not exciting so please don't read into that too much, haha.
I think this is some recency bias from the string of specific games I've just played but what is with these yanderes who are the flirty/super cheerful and/or younger types and then turn out to be yandere? Like, I feel like I vaguely remember maybe the first generation yanderes were all the overprotective onii-chan types so now they're overcompensating in the opposite direction or something? Although maybe I really just want some more lower register yandere voices in my ear xD like going back to something closer to your Kuro. The flirty/cheerful/younger types tend to be higher pitched so even when they go "dangerously low," it's just not quite the same.
Might see if I can cram in Ashen Hawk next although I hope it doesn't have too many more childhood friends/connected in childhood because I'm starting to get a little burnt out from that trope from playing 7'scarlet and BB back to back, haha (there is literally only one route in 7'scarlet where the LI has the normal reaction of...not remembering MC from a single interaction they had when they were like 4 /facepalm). Ah, I had heard good things about Collar x Malice but I don't have a Switch either orz. I'm pretty much confined to PC only right now but someday! Hadn't even heard of Steam Prison yet but it's available on PC (yay!) so I'll throw that in my list too. I also never got to do Ray's route in Mystic Messenger, alas, since I stopped after the base game pretty much too (needed too many hourglasses). Sounds like you have a pretty good collection in your backlog, I'll swing by for an update if I get through Ashen Hawk in case it helps you reorganize your priorities xD Happy weekend to you too!
Edit: Finished Ashen Hawk - I really enjoyed the MC (crossdressing as a guy and acts as a guy means we actually get scenes where the MC is not just a damsel in distress!) I'd say there was one ending that struck me as actually yandere. It's too bad there aren't really "bad endings" in Psychedelica because there would have been a lot of potential for that here. In short, Psychedelica again proves itself to be more of a tragic/philosophical sort of game (not a bad thing!) along the same vein as Black Butterfly. They do push a "true LI" a little harder than BB, though, which I tend to have mixed feelings about and I thought BB overall felt a bit more cohesive all said and done. I thought AH could have been great as just a standalone medieval setting game instead of feeling like they forced the Psychedelica aspect of it somewhat. Anyway, the MC in AH is definitely better, the setting feels fresh, the romance at times was a little eh for me, and the yandere itch was kinda scratched in just one ending but the game overall is enjoyable enough to overlook those other parts.