Not sure if this can be recommended without caveats yet? The %sub macro and friends were only introduced in RPM 4.19 (https://rpm.org/releases/4.19.0) so this is not available on EPEL 9, for example.

Also, the index starts at 1, not 0.

From the EPEL side, it's understandable that we'll need to carry some notes about packaging things that no longer apply to Fedora but still apply to one or more EPEL branches. We used to have a lot of EL6/EL7 things on this page. We can certainly add a note about sub and friends not being available before EL10.