Yeah, KOReader isn't superintuitive. Not blaming the developer at all; I much prefer the ability to, say, add new fonts over being stuck with whatever someone else decided I can use.
It's like in the retrogaming handheld world, where you can go with something like Retroarch - which you can adjust to be as plug and play as can be, and it'll still require some basic knowledge - or you can get an Android handheld and just play your games from Play Pass or whatever in case you don't feel like figuring what does what.
For me, tinkering with these things is fun, but I suspect most people just prefer the plug and play aspect of it.
Also: @ohIdon'tknow how tech-savvy are you? Ever thought of taking this KOReader port project yourself?