Chat seems to be focusing on EUIV and CK2 stuff right now so I'm not sure if he's going to continue the work for this mod. However I think all three most important scenarios Genpei War, Onin War and Rise of Nobunaga are all finished and you can play them with no problems.
I think he stated this is abandoned, pretty much.
From what is there I have to say Genpei war is my least favorite scenario, since the Taira and Ôshu Fujiwara are super-blobs in that one (and really, squishing Sengoku's "feudal" system into the late Heian period just rubs me the wrong way as a scholar of early medieval Japan...since literally everything was different back then compared to the 15-16th century). Whenever I tried it the Fujiwara ended up flooding the entire map since they really can't be pincered.