Depending who wins civil war or what Germany involvement in it is I could see them give back Ukraine to Russia minus Crimea. Romania gets Moldova plus Odessa in exchange they have to permanently renounce any claims to lands in Transylvania or that Austria holds.Belarusian nationalism was never very widespread or particularly powerful. Ukrainian nationalism was big during the Russian Civil War but cooperation with Germany seriously harmed their credibility in the eyes of the Ukrainian people, weakening their hold on power. Honestly it's a bit ridiculous to call yourself a nationalist while facilitating your nation being turned into a German colony.
Poland is extended East into its Ukraine claims. This does multiple things for Germans benefit. One creates buffer from getting rid of Ukraine and Belarus. Two gives a place to deport Poles or “encouraged” them to move out of German Prussia to help Germanized that region.There was a Belarussian nationalist movement during the civil war and the German government wouldn't allow the Polish to have too much territory as they would not want them to be too powerful. Also, Ukrainian nationalism was very big during the cvil war, both Belarussian and Ukrainian natioanlists would revieve continued German support. You could also apply the same logic about a Russian population explosion to Ukraine and Belarus, execpt it would be greater due to there not being a Holodomor or Hunger plan by the nazis (which affected those region more.)
The Baltic acts as staging base if Russia ever tries anything thing especially if Germans installed semi dependent weak pro German regime during civil war then the capital might be in St Petersburg’s and German military not stationed far off.
Also give pro German Finland all of Karelia, Murmansk, and everything north of St. Petersburg. Let Russians keep rest of its empire especially in Asia to help Germany project more across Eurasia especially if British take out defeat in ww1 in Ottomans to get something out of war. Might have to throw them under bus(ottomans).
Japanese are interesting because I see them playing both sides and “seeing weakness” on British behalf if Germany wins. Might get bold and even flip sides or strike deals with Germans who can’t really project in Far East especially if Japanese refuse to give back their colonial holding there. Maybe force French and Russian to concede to land to Japanese and concede more to them in China so they are least cordial with them and start turning against former entente(mostly France and Russia. Maybe Dutch. They might still be timid to test British navy).