Free Plan: I'm in the US, but I have Alexa set in Italian and my requests are in Italian. Alexa understands my requests ("I will play x from Spotify..."), but in reality plays something else.
If I prompt the artist from my iPhone with the Spotify app it will not have any troubles playing it.
I have the same issue when requesting a genre: last night I asked for Brazilian music, and it played "beer and wings" list. O_o