I’m not entirely sure, re-validation qualifies as a reload in the systemd sense since it doesn’t actually reload the config but really only triggers a validation run. For instance, if you change the RTR or HTTP listener configuration, that change will not be considered if you’d run systemctl reload routinator.

Currently reload is unused, just to fill it with something until the described full reload is implemented?
E.g apache reload is 'graceful' , one has too restart to add new module
Named reload in most cases is rndc relpad, i.e zone reload. I dunno, incomplete reload as opposed to restart seems acceptable around.