Where's the line between 'should', which of course is subjective, and 'reality on the ground'?
What of Kerelia - the annexation of Finnish territory by the Soviet Union? 400k Finns left/deported into the rest of Finland, with a new Russian population transported to replace them - in Finland, it's a dead issue. There are people who campaign for the return of Kerelia to Finland, but there are probably more Brits who are active Jacobites....
What of Poland, Germany and Belarus? Countries and populations who were shoved 100 miles westwards at the end of WW2 by the Soviet Union - I know a woman who lives in western Poland who's house was once lived in by Germans - German newspapers in the loft, pipework made in Germany, Polish road signs bolted onto the original German ones. she found a picture online with a German family playing in her front garden....
What of Crimea or other bits of Ukraine - they are unlikely to ever be part of Ukraine any time soon - in some bits the population has left, in some parts the Ukrainian population remains, 'Russofied' with compulsory military service, passports, and the Ukrainian language driven underground...?
Kaliningrad/Konigsberg?
This isn't 'suck it up, cupcake', or meh, it's more 'if you get to choose the 3rd century as the start of history, why don't others get to chose 1947, or 1945, or 2014?'.
It's a can of shitty worms.