A good ABC-to-MusicXML converter would be a great advantage. It would allow us to send our ABCs to owners of Finale or Sibelius etc. without losing their decorations.

Multiple parts (voices), lyrics, dynamics, and ordinary ornaments should be supported. These are sufficiently standardized in ABC, if only by the de-facto standard abc2pc. I would not worry about other fancy stuff.

Snail/Bryan, are you still on the project, or do you consider taking it up again, so that those "months" are not wasted?