In practice, I've added a few redirects to the nginx config on our
current server. That's probably ok as the subdomains still exist. Here's
the entire DNS for Scheme.org:
<https://github.com/schemeorg/schemeorg/blob/master/dns.zone>. Of those
subdomains, r5rs, r6rs, r7rs, and s7 are currently configured as redirects.

I can add a similar redirect for lips.scheme.org provided that GitHub
pages doesn't track users, or we could work out a way to host the site
on our server.