This was fascinating to dive into for a little while. I'm not sure I'd enjoy it, but now I'm curious to read one of Keeler's absurdly improbable mysteries.
Seriously, Alan Moore did something like this for Big Numbers. Essentially a big spreadsheet on A1 paper. Time across the top, characters down the side. There's an HTML-ized version here: https://stuff.alienbill.com/jamesharvey/bignumbers/
From the description, the novel that was just two people talking sounds like a two-hander play with a single location. Waiting for Godot?
I know it didn't get many comments, but OP, thanks for posting this.
In spite appearances, you are in fact disagreeing with me, because when I use a phrase like "UML Sequence Diagram", I literally mean drawing it on paper with a pencil, scanning it with a flatbed scanner, and then making some minor adjustments in GIMP. I would never think of using a DSL like PlantUML, or something higher level that generates it.
