I installed much of the fluidsynth stuff in the synaptic packages, but all the sounds, run through outport "129:0 synth inport (2898:0)" becuase it's the only option that makes sound, but all the instruments sound like drums.

How do I remedy this?

I think you will need to provide a lot more information before anyone can help you. Please read this.

What application are you using to play the audio? If it's a GUI application, try starting it from the command line. Output to the terminal while the stream is playing might provide some useful hints.

If you could provide a link to the Aria Maestosa, that might also help, even if the version you are using is local to your system. Otherwise, a link to an audio file available on line that provides the same symptoms could be helpful. Also, do some audio streams play correctly?

Also, what distro/version are you using? Your user agent icon says Ubuntu, but user agent icons can be misleading.