I am a user from Finland with a German account, currently living in the US. Finland is bilingual (which I love!) but it doesn't expand to my music taste. I've never indicated to enjoy music in Swedish, still every week my "Discover new" playlist is half full of songs in Swedish. I press "dislike" for them, trying to indicate I would rather have music in English or Finnish (or heck, even German) but week after week since years half of my discover weekly is full of sad songs in Swedish.
It would be great to add into algorithms the song language (to notice customer preferences) - or even manual ability to control discover weekly with some criteria (e.g. language, genre, decade).