Can Mosaic export (reliable) XML?

Good question! I'll need to check it out...thank you!

You might ask at motunation.com to see if anyone remembers.

http://www.motunation.com/forum/viewforum.php?f=15 

I'm afraid that Mosaïc is pre-MusicXML. It is not on the list of compatible MusicXML softwares : https://www.musicxml.com/software/

Looks like you have to do it the old fashioned way via MIDI export:

https://motu.com/products/software/mosaic/other.html 

You will need an old Mac that can run the app and export. With any luck, you still have that Mac, right? Yea... A G3 is your best bet since it can run OS 8 or 9. The various builds of Mosaic were twitchy about which versions of the OS they would work. IIRC, Composer’s Mosaic was required for OS 9 and stability was a major issue.

Macintosh Garden is an excellent source for old builds of the Mac OS and various builds of Mosaic.

http://macintoshgarden.org/ 

Thanks much!!!