The actual version of VirtualMIDISynth (v.1.15.0) now support .SFZ soundfonts.
http://drealm.info/sfz/plj-sfz.xhtml
Maybe this format could be more user friendly.
Could it be supported by vArranger, too?
Yes I can add the SFZ support, but I don't know if there is a system to write the bank and program change number inside sfz files
If not, we need to add a custom opcode for that