I did a search here and couldn't find any mention of this. I don't have a MOXF to try it with, but it looks notable in that it runs as a web app that is mobile/touch friendly.
And, of course, it is open source!
The app:
https://josephdouce.github.io/moxf-editor/
The source code:
https://github.com/josephdouce/moxf-editor
Rubbish.
Doesn't work at all.
Probably uses webmidi which is limited to supporting Chrome and Opera only (on PC). Not sure about other platforms. I haven't tried using this myself.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R
It is still under active development and has just received an update:
Now has librarian features, you can switch modes and select voice, song, perf, master, mix, pattern from librarian page.