No, midi files do not contain the information of what sample library is being played.

Instead of MIDI, MusicXML carries much of that information.

For example, I master audio for a composer who uses Sibelius. He doesn’t care much for the sounds of those libraries and I have a few terabytes of VIs. He emails the MusicXML files to me. I then open them in Notion which automatically assigns the bundled sounds to his tracks and lets us know if any instruments are missing (such as mandolin and nylon string guitar) and I do a quick mock up of what I think his intentions are. He makes an appointment  and comes over. Together, we then go through the score and reassign instruments where he thinks they might sound better using Aria, Kontakt, SampleTank etc. pan and adjust the overall balance using the mixer. Bounce the resulting audio to stereo and it’s ready to master.

I could do this in Finale just as easily but he prefers the basic instrument set that comes with Notion 6 (an $80 cross-grade from Finale, Sibelius, Dorico etc.) over GIFF so it’s faster for us (and less expensive for him) to start there. Like GIFF, the included Notion VIs cannot be used in Sibelius but MusicXML makes this task quick and easy.

Another option would be to import the MusicXML into Logic Pro and assign other VIs there. If the tracks were destined for export as stems, needed heavy processing or were to be overdubbed with multitrack vocals, I might choose that option. Again, MusicXML saves time over MIDI in this regard. It preserves more of the performance though, like MIDI, the actual sounds are not saved.

Yes, having watched me work, he could spend the $80 and do what I do but I have a few thousand $$$$ of other VIs so he considers working with me as money well spent. I do nothing to discourage his thinking on this, of course.