Since the wavetable mapping was just a file of instrument samples, they could have just made their own, but they instead asked roland to do it for them, who they deemed as the best in the industry in this regard. Roland decided to strip down their most popular patch(SC-55) so it would sound good on midis designed for the SC-55, but still make purchasing real midi hardware hold value. And that is why microsoft has the midi patch it has. Onestop.mid was one of the midis meant to benchmark the wavetable solutions, hence the way it is many genres rolled into one. The main issue with the patch microsoft used was how short the samples were. More reverb by default could have helped the poor decay of the microsoft patch. I uploaded onestop.mid played on the full sc-55 patch on my channel(No extra reverb). It sounds so much better than the microsoft patch. Adding extra reverb would make both sound even better, but I thought it would be cheating to add it when you couldn't add extra reverb to the midi emulator on windows.
the jv-1080 is a proper digital synthesizer, so you wouldn't just be able to use just a sf2 file. you should look into getting a vst, plenty of "free" options online ;)
People have been making soundfonts since the '90s, I'm sure there's a JV1080 soundfont if you search. It might end up being on archive.org only by now.
