Finished redoing my jazz compositions (50+ of them!) in MuseScore

Great! You might want to check out my tutorials on lead sheets, then, as most likely there is other stuff covered that might not know about: http://musescore.org/en/node/11723 and http://musescore.org/en/node/11726

I notice also you are using "m" for minor and "dim" for diminshed. The default template doesn't recognize these abbreviations (it uses "mi" and "o" ) and as a result, chords using those abbreviations will look strange ("b" not turned into the flat sign, etc) and they won't transpose correctly or export to MusicXML. See http://musescore.org/en/handbook/chord-name for more on the various options available. If you wish to continue using those particular abbreviations, you could try switch to the stdchords.xml style in style / edit general style / chordnames, and then force MuseScore to reparse the chords by double click then and hitting space (you could double click the first then just hold space while it cycles through all the chords). The flat sign used in this chord style will be the "generic" flat sign used, though, not the MuseJazz version. I don't think there is a direct way to get the abbreviations you are using while getting the full use of the MuseJazz font. But you could edit the chordname style file to get that if you really need it.