As you might know we host an old archive containing the abc2xml source. I've looked up the wayback internet archive machine but unfortunately the xml2abc.xsl files is not archived (the xml2abc.cpp source file is empty, probably due to the fact that with the xsl file there is no need to write any code).
There is a abcusers mailing list at yahoo:
The group is moderated and access to it's files requires membership (reading the list is possible).
I've found out about one python tool and a java tool but haven't looked closer to them yet:
Also there is the online converter:
Also there is the MuseScore abc/xml support:
That should be enough possibilities to get abc source running with Canorus (and maybe a base for the Canorus import/export filters).