Re the Java thing, as far as I know, there is just the system MIDI but I perhaps didn't spend as long as I might have looking at it. When I did look though I did not manage to find a way to select a MIDI device rather than just use the systems first free devices. On my (Linux) system, I assume it is using alsa.

Still on my (Linux) system, with Java I do get the sound delivered to my keyboard which is what I want. The python one I had an even briefer look at seems bound to gstreamer and I've been unable to find out how to get that to use anything other than the timidity software synth...

But I'm easily confused with Linux sound. There just seem to be so many bits that may or may not be involved and so many possible configurations. I do find it a real maze.