It’s such a shame that the Common Lisp community has to rely on archive.org so much. I remember working with others to recover (IIRC) https://wiki.alu.org/ from archive.org after... something.
Yes, it is unfortunate. Information loss on the internet is not limited to CL, however, and many of my bookmarks became stale over the years. When I encounter a "treasure trove" of information, I make sure to archive it on my machine (and ultimately on backup hardware). Sometimes I put it up on sites like GitHub.
I tried looking for this on QL and github but couldn't find it ... do you know if the common cold source code is still available somewhere?