New updates were released with many welcome enhancements, see http://backuppc.sourceforge.net/BackupPC-4.1.3.html#BackupPC-Introduction Version 4 is fully backwards compatible with existing version 3 installations. Thus, if the maintainer is willing to update to 4, there are no issues with releasing the updated packages in EPEL. Will you consider an update?
As I have mentioned on the backuppc mailing list, the problem is not that the pool changes are not compatible but that there are configuration changes which an upgrade can not be guaranteed to map correctly breaking someone's installation. Another option would be to have a BackupPC4 package for those that want to use it but there are a few problems with that route as well. I don't have a lot of time and the original 3.x version prior to my taking over maintenance violated the Fedora packaging guidelines in a lot of ways. I have made many improvements over time but I still don't believe the package would pass a review today. Those that want to upgrade may use my COPR which I have kept up to date. https://copr.fedorainfracloud.org/coprs/hobbes1069/BackupPC/
I have created an issue upstream (https://github.com/backuppc/backuppc/issues/127). Perhaps there are possibilities to ensure the configuration of v3 is also compatible with v4, thus eliminating the need to maintain separate packages.
Do we need to leave this bug open? My COPR is available for anyone who wishes to update and I will continue to maintain it, but doing major upgrades within a RHEL release is highly discouraged.