Maybe the problem is that that the sound file is in OGG format?
Recent versions of libsndfile support ogg/vorbis and the build shipped with Debian seem to support it as well (at least it requires libogg and libvorbis). I've never used Renaissance and I'm not sure how it handles the sound tag, so I'm not sure I can help you here. You have all the requirements to create and playback a NSSound. At this point, you're going to have to wait for someone that knows how Renaissance works, because I have no idea what the sound tag does.
To tell you the truth, I think you're the first person to really test sound playback since I reimplemented it over a year ago. It's nice to see someone is taking advantage of it (or in this case, not so much). Thanks.