The upstream repo for kmscon is https://github.com/dvdhrm/kmscon, which hasn't seen updates since 2014 and has some outstanding issues. Perhaps the most annoying is the incorrect escaping of characters in tmux, leading to random characters being printed when tmux is run inside kmscon.
https://github.com/Aetf/kmscon was last updated less than a month ago and, though it hasn't had an official release since before the fork, the master branch contains fixes and improvements that likely will never make their way into the original repo.
Attached are updated ebuilds from my person overlay that use the forked version of kmscon.