There are many ways to express that in Russian. That's true the example is not the best, but the question is clear. Perhaps, a better example might be something like: "She doesn't speak American English, but she does speak English." (Pronounced with the British accent).
As a thought, I think that "does" stress is a bit informal in English, so why not to give some of the informal equivalents in Russian? Some of those would be:
1. Она не говорит по-английски, но она таки говорит по-русски. (This is a very specific dialect in Russian, so use with caution.)
2. Она не говорит по-английски, но она вполне говорит по-русски.
3. Она не говорит по-английски, но она очень даже говорит по-русски.
4. Она не говорит по-английски, а вот по-русски - вполне.