Sounds very interesting, and your story shows that there’s no substitute for tribal knowledge...
It was an interesting team. 25 people. All the original developers of the systems being transformed from standalone web servers into a modular architecture capable of being "scripted" to allow workflows across the components. It worked well, but required huge servers that could load up all the kubernetes managed components. Rooms full of dedicated servers were replaced with...rooms full of shared servers. The tribal knowledge of the old systems and required interactions was critical to the success of the program. Even more fun was having some of the system running under Linux and some under Windows and coordinating the show.