No, we're using the NDK, so there's not Java directly involved.
Java API for C++, how would that work?
Well, that's exactly what JSFML is. Except for a few types mapped to Java, all the functionality happens in plain old SFML. The delegation is implemented natively, ie in C++.
Android support is not just a binding, but it's built into SFML. You use the NDK and set the right CMake flag and you end up with Android libs.
Hm, that means that JSFML should work fine on Android if the delegation was compiled for Android as well and included in the package. Other than that, no changes should be required.
However, Android development is uncharted area for me and I am one of the few people left that despise mobiles...