Hitler as he used to do with any minority in Poland ,considered Highlanders “german”. Actually Highlanders are one of the most pure Poles and speak dialect of Polish language. They basically speak Polish but they use some diffirent words or simply same words but pronounced differently. But its mostly about accent. They all speak basic Polish but they have their accent that is hard to imitate. Its nothing like any other Slavic language.
Romanians are so mixed that they dont know who they are themselves so how could they make such ridiculous claims?