And so the mystery deepens. There may, in fact, be an issue with ALL of the strings pitches in the conversion rather than the other instruments (which would sound wrong by comparison in a mainly-stringed file). I just did a side-by-side listen back of the entire soundtrack (originals vs my midis) and tracks that are 100% strings are all slightly higher in pitch in the midi files, so now I'm going to see how things sound if I re-pitch just the strings. As near as I can tell, I need to -250 all the string pitch wheel values, but it very well could be just -200, but it's very hard to tell with a minor difference like that. -250 gets me -250 to 0 range for most of the values, where -200 would get me -200 to +50.

Hopefully I'm down to the final stretch on this soundtrack, where I can start the finalizing/tidying/tagging soon!

EDIT: Doh, no "one size fits all". I corrected 2 songs, then the next song already had correct strings pitch. Ah well, such is the process.

There are 2 RPN messages for “Channel Fine Tuning” and “Channel Coarse Tuning” in the MIDI 1.0 specification. Many MIDI devices support these.

RPN 01 - FINE TUNING:
Resolution: 100/8192 cents
Range: 100/8192* (-8192) to 100/8192* (+8191)

Control Value Displacement in cents from A440_
MSB LSB
00 00 100/8192* (-8192)
40H 00 100/8192* (0)
7FH 7FH 100/8192* (+8191)

RPN 02 - COARSE TUNING:
Resolution: 100 cents
Range: 100* (-64) to 100* (+63)

Control Value Displacement in cents from A440_
MSB LSB
00 XX 100* (-64)
40H XX 100* (0)
7FH XX 100* (+63)