Translation:She is not speaking Swedish but Norwegian.
I don't think so. Without a context "She doesn't speak Swedish" means she doesn't know Swedish. However, you could say, "When she is in Oslo, she doesn't speak Swedish, but Norwegian." But to be clear you need that adverbial marker to call for the simple present. Otherwise, you would have to say, "She doesn't speak Swedish, but she does speak Norwegian [although it doesn't matter because they understand her in Stockholm anyway]."