If you want me to be honest, Kusari initially lost whole KNF, save for the stationary ships, planetary squadrons and the self-defence regiments that had no role within Taus. Then there was a coup, Kusari turned Republic for some odd reasons that I cannot really understand - especially in a House in which industrial control of 4 out of 6 system belong to Samura. They would surely secure any possibily of coup...
But that happened yet it's no point discussing it beyond that point. Emperor exiled, Dragons lost faith in Kishiro (enemy of my enemy, etc.), Kusari turned Republic and these are current circumstances. Kusari made a fragile peace with Gallia, suprisingly without much of any stress onto New Kusari, especially with easy access into Kusari from two bordering systems.
Kusari, however, isn't on the very same terms like Empire of Tamriel from The Elder Scrolls. Sorry for bringing up different universe, but at least Aldmeri Dominion and Empire of Tamriel were on relatively equal terms when the war had ended with relative peace and banning Talos worship. But in reality both armies were exhausted and suffered heavy losses and whole White-Gold Concordate is just interim peace to buy Empire time to strike back at the Dominion.
Such a situation doesn't happen in Kusari, however, which - according to story devs - lost much of a core fleet due to stupidity and ambition. Gallia has upper hand and ruined both BAF and KNF back then, kicking into exhausted battlefront and KNF was ruined - so it would be logical to install a Gallic governor rather than allow Kusari to be... whatever it is... especially in wake of Civil War. Up to this day I cannot really find much piece of a rumor if Republic of Kusari is controlled by Gallia or not. However, I always supposed that Gallia let Kusari strive due to pretty obvious reason: economy and imports. I'm not sure if that was retconned or not, but Gallia was said to almost deplete all of their resources onto massive GRN - putting them into pretty much situation like Liberty, which according to the lore do not have any resources - the very reason why there was Liberty Navy (or LSF, it was never explained) in far away Sigmas.
Going off the subject, I can't really understand however how is Bretonia still standing? Kusari had no industry losses as no war (except for domestic one) ever took place on their own soil - but Bretonia? They lost industry and are incapable to create even half of former efficience - according to that, Liberty should be hit as well (remember, Liberty heavily depends on imports because no resources). I'm asking, because I do not really think Rheinland would be, after past war with Liberty, be so glad to deliver resources to the guys whom they shot "just recently".
Why I poked up Bretonia? Because, more or less, Bretonia should be the one bending their knee to Gallia in the early stages of Gallic Invasion right when Liberty was pretty busy with Rheinland and couldn't fight on two fronts at the same time. Thanks to Junkers who served as spies, Gauls knew more about Houses than Houses know about themselves, unless that got retconned as well.