Reference distance is the earrape distance. I'm not sure why 2d datablocks even need a reference distance. They shouldn't be falling off. Which is why you can still hear it no matter how far you go.
Also, the huge difference is that reference distance and the is3d values, the support script was modified to accept the is3d value instead of always assuming 1.
This is why I said "Done. Was easy." Because it really wasn't that difficult. Of course, because of other add-ons containing the same support script, I had to modify it and put it on a scheduled execute.
As for the volume, I'm not sure if I can do anything about that, I'll take a look at things.