... so your track is: Larian sells DOS2 to Russians without any earning . And that is ok for you, but problem is when Polish want to buy a game from Russian... pity... and the problem is with Polish...not Russians, not GOG/Steam pricing, not with publisher ...very, very pity...
You know, that's a good point, actually... as far as I know, after deduction of taxes and Steam/GoG's share, usually a little less than 50% of the sales prices goes to the developer. So from the full Steam/GoG price (~200 PLN) Larian would receive approx. 100 PLN. From the Russian price (~50 PLN?), they would receive approx. 25 PLN. That's a significant difference (especially given how much money they put into this game), but you're right, they should still receive a share of the Russian sales, and they would receive that same small share if you got the regional pricing in Poland that you are requesting, so there's no difference there.
My point about how this would affect sales statistics in Poland (and thus possibly the willingness of Larian to do a Polish translation) still stands, though. If you want these sales to count as Polish sales, then I really can only recommend to wait until the salesprice of this game in Poland is lowered to a price that you're willing & able to pay for it. If that doesn't matter to you, then sure, go ahead and buy it from a Russian reseller. It definitely is a much better option than just playing the game without paying for it, as the OP suggested.