The issue I'm having is that the administrative subdivisions sometimes ignore existing ethnic divisions, and there does not seem to be any higher level of territorial subdivisions. I can't see the Poles having _initially_ set up a political system in which Poles could be outvoted by early 19th century Germans and Russians, so I wonder how this evolved.
Economic union, set up by the Poles to ensure that Europe would never go into a huge war with itself, and that it would be in an economic alliance, similar to the EU, but with Warsaw on top. Confederation of Germans into larger nation-state. Russian revolt against their autocratic rulers, devolves into anarchy and a Russian state is established under heavy Polish occupation. This is all by 1830s. Peace reigns in Europe, Germany and Russia modernize, the elites growing more and more in touch with Polish sensibilities. The Internet and other modern amenities spread throughout Europe and gradually the rest of the world, and by the 1900s, every educated European speaks Polish. Eventually, they decide to start doing away with pleasantries like borders.
Are Germans and Russians Polish? No. They consider themselves Europeans, and Europeans just happen to speak Polish as a common language. Polish at work, German at home.
The state with the Polish color is the European Economic Association (in English, a sort of common language on this world, quaternary to Polish, German, and French in economic circles). The capital isn't even in Warsaw, it's in Vilnius.