EB and I both worked at Lucid, which produced a Common Lisp system, not to my knowledge a version of Emacs (though maybe so after I left in 1989?). Some other early employees knew and liked Lisp, but we didn't use it on any core functionality. The text substitution logic you mention, that I wrote, was really simple and not particularly Lisp-like. Though again, after I handed it off, who knows what happened.
Lucid Emacs -> Xemacs was mentioned in a sibling comment, but I remember people being in awe about EB working on those. There were many interesting employees back then--J. Chenault, J. Gehlen, R. Braumeller, F. Eiden, K. Sears, etc. I've lost touch with most of them but I learned a lot from them.
I started in October 1997 and did Perl work on backend systems, but I had a few friends who worked on the frontend. They used to talk about how Catsubst had a very small set of verbs and that everything was a function, even arithmetic, and that prefix notation was used for all macro calls. They thought it was Lisp-inspired, but they were also pretty junior programmers too. I never worked with Catsubst myself, so my information is second-hand, while yours is zero-hand since you wrote it. :-)
Thanks for all the work you did on Amazon's infra!
Yes, there was a ton of Perl in the early days. This came about because Paul Davis was a Perl aficionado and did a lot of script writing with it early on, and the non-programmers, of which there were n-2, could pick it up much more easily than C (of course). Which is how some of them became programmers. Incidentally, we used C, not C++, though I liked OOP, because I had previously had less than great experience using C++ on large projects. We used a C++ compiler though because it could catch more errors than the C compiler could. This is one area where Steve Yegge was a bit off in that famous post.
After leaving Lucid I was really not paying much attention to what they were doing. It wasn't long before things started going badly there and they were out of business a few years later. But indeed, I had forgotten what little of the Emacs history I might have known. Here it is: https://www.jwz.org/doc/lemacs.html
