I've never played Russia myself and from what I've seen here it may be a bit too hard for me....
Brandengurb III has limited himself severely with many house rules. A fully emancipated, constitutional, liberated Russia has about 80-90% of its population as state cultures (russian, belorussian, ukrainan, polish), has a lot of resources, and can be turned into an industrial giant, but requires a lot of micromanaging.
Brandenburgs appraoch, opting not to liberalize, to remain a backwards, opressive, very much OTL Russia resulted in what these policies resulted in OTL: a mess held together by the army.
Still, a very nice gameplay considering your self-inflicted limitations. Sault, I say.
Excuse all the errors, I'm getting sick.