as far as Russian speaking population is concerned, i think that unfortunately its large part represents mentality alien and at times hostile to the Western world, therefore for a society which associates itself with this world it poses considerable hindrance
I was recently in the Baltics and noticed no such mentality among the Russian speakers. In most cases (except the market in Riga) it was very hard to tell who was ethnically Russian vs Latvian. They are not very warm people, like Ukrainians for example - but both groups were about equally well or poorly behaved. There were crooks and rude people from either nationality, nice and friendly people from either. The Russians are somewhat the underdog though, the native Latvians are a little bit better off economically I think.

And no, I do not support any of the pro-immigration nonsense, but that is a completely different question. The current generation moved there. They are first generation immigrants who consciously moved to Europe and have been well taken care of. As far as the Russians in the Baltics and Ukraine knew, they were moving within an existing nation and had not done anything wrong. I am not saying that the Russians in the Baltics should not try to learn the local language. I absolutely think they should. But the Balts are practically being fascist about it - that is what I oppose.
And I support the EU's acceptance of minority languages - it works well, everyone wins, everyone is happy.

And if you do not like immigration from Non-european countries, then you can thank your lucky star that your country was in the USSR! Otherwise you would have as many non-Europeans as we have in the EU, looking different, speaking differently and with different culture. The Baltic states are essentially culturally and ethnically homogenous from an outside perspective, which is more than what can be said for any country in Northern Europe for example. In Belarus were only Belarussians and Russians, in the Ukraine I was not able to determine, but there certainly were no Africans or Arabs there at any rate. In Latvia too, were only white people, Europeans.