If you're going to further update this program, I'd suggest immediately focusing on subtitles on each page, copyright information, and page numbers, because those (besides the measure numbers you already added in) are the only things a MuseScore user can't get in the MUS that's required for formatting.
The uh... "Pno." thing could already be removed without any need for a program, btw.
Those'd be hard though, because the way MuseScore sets up those bits of text is different from Finale. Impressive what you've done so far regardless.