From https://qubes-doc-rst.readthedocs.io/de/latest/user/templates/templates.html (first link on the page you were reading):
In Getting Started, we covered the distinction in Qubes OS between where you install your software and where you run your software. Your software is installed in templates. Each template shares its root filesystem (i.e., all of its programs and system files) with all the qubes based on it. App qubes are where you run your software and store your data.
– so by that logic, sys-usb/sys-net/sys-firewalls should not be “Templates” but “App qubes”.
Edit1:
Wrt. the reinstalling of sys-usb/sys-net/sys-firewall, I guess you could use this:
and
Edit2:
Caution: “The pages are intended for advanced users.” – I’ve not tried any of it myself, but I would make a new backup of important files, read the full pages … and be prepared to either restore from the backup or cry a lot.