This does mention Archy, but not in any depth. It doesn't mention The Humane Interface (https://en.wikipedia.org/wiki/The_Humane_Interface), THE, or RCHI. I wonder what the reason is for these omissions? You'd think they'd be central to any discussion of recreating the Canon Cat document interface!
I wasn't familiar with (or had forgotten) those acronyms nor Archy. Looks like RCHI stands for Raskin Center for Humane Interfaces. THE stands for The Humane Environment which is what Archy used to be called. https://en.wikipedia.org/wiki/Archy_(software)
Sounds like it had the problem of not using a custom keyboard.
Bootstrapping Computing looks interesting.