Is it theoretically possible to generate a sf2 file (a soundfont) since dosbox can dump it's FM synth music in a wav anyway?

FM SoundBlaster Emulation really would be faster in that case.
You should load a soundblaster sf2 file in the soundbank for cards who support it, eg sb live! and set general midi in the setup of the dos game.

I believe windows midi is being used anyways in that case?

That way speedy "fm sounds" would be possible...they're kinda slow for now

Just would like to know