'Fraid you can't batch process SMFs for volume unless they were all generated by the same soft arranger (and even that's a stretch).....

The problem is, how does the batch processor know the loudness of a track or sequence? Sure, it can look at MIDI volume (CC7), but how does it know the average (and range) of the velocities...? Then how does it know how acoustically 'loud' the synth patch is?

Unfortunately, if you have got SMFs from a variety of sources, only way to balance them is to play them and either globally turn down the sequencer section volume (doable at least on Rolands, and maybe others) or you have to go in and change the volumes of at least the individual sequence tracks headers, and if any fades are done with CC7, subtract from those, too (or scale - reduce by a percentage).

Take a good look in the MIDI section of your manual. There may be a sys-ex command to globally turn down the sequencer in there even if there isn't a GUI front-door to the function..... If you can find that, you will be saving yourself a lot of time if you have a large library.