They speak with a German accent because Upper Sorbian is spoken that way today, including the R which sounds totally German, also when spoken by older speakers. In songs, it is sometimes rolled though.
I remember looking for samples of the languages spoken by natives of Siberia. Some of those languages were phonetically similar to Slavic languages due to Russian influence, because the natives speak Russian everyday. A good example good be Finno-Ugric languages of Russia and Finno-Ugric languages of Finland, Estonia and Hungary. The former are heavily influenced by the Russian, while the later sound foreign in my ears.
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