Shiichan sucks and is written in PHP. Kareha sucks, is written in Perl (which causes more issues than anything else ever could when trying hard to do so) and doesn't scale well at all, seeing how a board of just the size of 4-ch needs to use archiving scripts in order to keep things running smoothly.
why not do it yourself.
Heck, I have a quick prototype of a textboard written up (in go, no less). It was a fun little project.
It's hard to say what you are looking for and what exactly is your problem with all the other software. But despite more than seven years have passed by and you may already have found something, I just want to chime in dietchan: https://gitgud.io/zuse/dietchan
You can take any imageboard engine and just disable image posting. Or install forum software you like and make possible to post without registration.