@AMIGASYSTEM
On the topic of Wild:
1) License - it is ok to upload GPL-licensed software. You don't have to include neither sources nor documentation in the archive, but you need to include a README file with an URL of where the sources can be obtained.
2) For replacing the older version, the idea solution would be for you to change source code such that the config file is read from one location not from each location of midi file. It might be as simple as finding in source code a place where a config name if given and the adding ENV: before it. So if you know the config file is named "foo.cfg", find in source code where this string is present and see if changing it to "ENV:foo.cfg" make it being read from one location.
I leave to you the decision on whether to upload your compiled new version to Archives. If you do, I suggest to replace the older version.