This is very nice, regards on all the effort I'm sure it took to prepare it make it so presentable.
But, I have a quibble.
Simply, 800 years is a LONG time. It's been 800 years, and the galaxy is still in chaos.
Something(tm) triggered the formation of empires such as the Vilani, Consulate, and the Imperium. Those were too long lived to simply be the charisma of a single leader striving for power or unity. It suggests some other galactic societal need for structure.
The Vargr are apparently naturally disorganized enough to not unite into a singular power, and thereby suffer from it as a whole, and, by extension, inevitably, individually since there's no tide to lift all boats with Vargr society. Otherwise, their quick recovery should have triggered a fast wave of expansion as their new power overtook the recovering neighbors to consolidate them and place them under a new flag.
The idea that they simply leveraged that advanced start as a more dangerous pirate force denies a fundamental need of piracy -- functioning trade and society to prey upon. Pirates don't prey on weak neighbors. Weak neighbors don't have anything, and when weakened more (by things such as rampant piracy), they just grow weaker or fail.
Rather, pirates prey on strong neighbors in weak places. And the thing about strong neighbors, is they can reinforce and project power into weak areas, especially when riled up due to crazed marauders interdicting their people, trade, and treasure.
The Wave had a very large impact on human society. Societies don't take well to losing 1/2 their population. But, this was, essentially, the impact of what happened to Europe with the Black Death. But, that said, 100 years later, the Renaissance was firing up, and complete in 200 years. This from a society with no "real" technological foundation (I agree, that's a bit unfair and jaded, but...). While humanity was greatly impacted by the wave, their foundation wasn't, necessarily, set back that much. The fundamental knowledge of Jump was not lost, nor abundant power, etc. Set back for a bit, sure, but just waiting behind an unlocked door to come back roaring, and roaring it would. Humanity was not knocked back to the stone age and dark times having to relearn fire and wheel. It was bruised and battered, but once past, able to pick up where it left off, perhaps with a new mission of expansion to make up for lost time, or a drive of "fixing what was broken before" (not necessarily to great success, our ideologues aren't necessarily the most practical thinkers).
While perhaps sick of conflict (for good reason), that would not prevent them from expanding rapidly to consolidate to whatever border was appropriate. But they wouldn't just let the other powers push back. I think they'd come in with the history of what happened before, with a "we shouldn't let this happen again" philosophy. The biggest power struggle would be to thwart these Corsairs. The Corsairs could well be reason to re-unite under a larger banner, if nothing else to rally a navy to better resist and deter the Corsairs.
While the Vargr may enjoy their small groups that can not reconcile, Humanity, historically, has not had as much of an issue with that, and has historical analogues and doctrine to build on, and to not build on (the "Well THAT didn't work!" syndrome). They would push back, I think, and it would not take them 800 years to do it.
So, anyway, after all that, just seems to me the galaxy is in too much chaos for such a long period of time. Nature abhors a vacuum, and at least Humanity more so than not progressed and prospered under the auspices of the Imperium and Zhondani Consulate (for all their problems and failings). There can certainly be some manner of balkanization of the old Imperial holdings, but, at the same time, there may well be drive to work, again, under a unified banner -- it all depends on what the existential threats are. Clearly the Imperium expanded with some message of stability and progress, it wasn't just tearing through the galaxy, conquering everything through violence and destruction. It offered something substantial to make worlds willing to join. And the border areas trying to contain the Vargr are going to want some support from those inner sectors that it's holding back the tide of disruption from. "Through the blood of my people are your lands kept safe." That gets pretty old, pretty quick.
