What people are ignoring is that Kplug and HF/BR are at odds and right now, they seem to be irreconcilable. Why? Because I think both branches finally realized that after the feud, it became a race and the one who gets "there" first will get all the patreon money and kill the other forever.
What you can do, is manually install Kplug on BR updates, but I don't think some HF patches will work all right with Kplug. Yes the manual is not that "clear" about how can you achieve that spot, but if you read it "carefully" you can manage to install it and make it work. What would be nice is someone who knows how to install and has all the files, making a video on how to install on later patches like RX7/RX8 and HF patches above 3.2/3.5(I don't remember pretty well). I remember you being able to make all of them work together before the feud, around HF3.2, BRX5/6/, Kplug 2.4(public) I might be wrong on the versions.
I've not made one yet because I'm not playing KK, nor have downloaded any of these builds. But I'm quite sure there are people here who managed, just not sure about making it work alongside HF Patch. In the end the users win because there are 2 branches fighting for their attention, the danger in this path is that one of them could disappear entirely by twist of fate(very implausible due to engine). Koikatsu seems to posses more lengivity because it fills a niche the other games couldn't. It doesn't seem to require constant updates as a new game as the other Illusion games required. I see KK as being around for a longer time than all the other games because of its style in rendering.