So, right now, I haven't read al of the thread, so please forgive me if I may write something that has already been said.
To my mind, 2 things should be fixed to increase activity within Kusari again.
1.) Either get rid of the "republic" issue so that we have more rp-reasons for the internal struggles within Kusari again or set up a new war with another house
2) Fix the old cardamine trade route. Yes I am serious. In vanilla, Kusari was actually the primary route for any cardamine to Liberty. Now this way has come obsolete with the Baffin-Coronado route. I suggest that the latter one is being made less favored so that cardamine smugglers use Kusari to get into Liberty again.