I want to say that your Kurogane-sensei continues to be fantastic. His threads with Fay-sensei just crack me up so much. I can't wait for him to start interacting more with his students, which he's already started to do. His threads with students are always so sweet because you really get to see what kind of guy he is beyond just flailing at Fay being an idiot. I think you handle his silly side as well as his more mature side really well, all while making him still seem like he's very much the Horitsuba version of himself, not the TRC version.
I also think that you've worked through any issues that were pointed out last time regarding Takeshi. He definitely seems less mean and less closed-off, all while still being very much himself. I loved his thread with Erii. I was cracking up so much the entire time (and compliments to Spoon, too, since she hasn't yet posted to this meme). He's definitely seemed less harsh lately, without being oocly mushy or something like that. It's great to see, and I think you're doing fantastically with him!
I don't really have anything to say about Keiichi. I haven't seen him around lately! Although that's understandable, because he seems like he'd be a very exhausting character and if you don't have the energy to devote to him atm, that makes sense. But I hope to see more of him in the future.
As for Hideki... I still feel like you aren't taking advantage of his character/canon. You still seem to avoid opportunities to make him a little more dynamic or interesting. His characterization is down, but it seems rather understated. For example, the thought bubble thread with Miyuki: why not have him see the thought bubble? Why not have him react to something like that? Instead, he's kind of stuck in this perpetual :)-mode, and I feel like it wastes the really cool opportunities between him and Miyuki. Why doesn't he get more flustered? Why doesn't he get more embarrassed or unsure or uncertain? I realize part of this might point towards his canonpoint, in which he doesn't have the beginnings of feelings for Chii, but it still seems kind of off.
Not to say I think he should be an angst bucket or constantly in inner turmoil!1 about things. But right now, he just seems to fall into generic nice guy-ness, where he's always helpful and always smiling... but not doing much of anything else. Why not explore the fact that he's a healthy young man? Why not explore, more, how he feels with/about Miyuki or other girls for that matter?
I'm not saying you don't ever do this. Because you do. He's had some really interesting and lovely threads with some of the girls on the island. I just wish we could see more of that and have you take advantage of Hideki's unique character, beyond just the fact that he's nice.
Ultimately, though, that all is kind of a small thing and it obviously relies on what you feel like playing and want to play. Beyond that, Hideki's characterization is great, and you've really improved on your other characters. You're always lots of fun to stalk and I can't wait to see more of your characters in the future.