AFAIK, Librerator hasn't been updated for a long time and has been lagging behind on all the bug fixes and new features from the new KOReader. The fork was mainly targeted for keyboard kindle devices at the time.
I just tested KOReader on my K3 last week and it works out of box. I also tested and verified that it works on DXG awhile ago. I am pretty sure it should work for K4 too. So yes, KOReader now supports all kindle models