Nonsense, that's called 'learning a language' and is done by many who move abroad. I'm Dutch but more or less fluent in English and Swedish, can come quite far

Nonsense, that's called 'learning a language' and is done by many who move abroad. I'm Dutch but more or less fluent in English and Swedish, can come quite far in German and make myself understood in and understand French. I'd have to learn local idioms in any of those countries, including the Netherlands since some expressions are really local and don't see much of any use outside of the village or county.