Well, I do not see Swedes expanding into Russia as something "off": even historically they did attempt that. Longer time back in the history they even succeeded... The first Russian tsar dynasty were descendents of Swedish vikings.
GB got to Poland probably after Poland attacked Austria (or vice versa) and the Brits sided with the ally.
I have seen an odd province 'ownership' here and there, but in most cases it's a result of one faction grabbing a tract of land and then, the original faction taking a few provinces back while still having an island of enemy controlled territory within.
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