HARMONY doesn't run on any version of MacOS and I don't now have access to a Windows machine I can load software on. (If it runs on Win98SE, I might be able to load that under the Sun emulation environment, as I have both lying around somewhere).

I doubt the tune examples would be a problem for it (they deliberately don't push the envelope with unusual ABC constructs), but I couldn't guess what the user interface would feel like. Somebody care to try? You need to be able to read the text and ABC source and play and/or display the tunes at the same time.