I'm in fact super acclimated with that file in particular. I've had zero problem jumping in and hacking around with it (been trying to cook up a FastAPI-like endpoint interface for async jobs/tasks a la Celery). Not a single line is surprising if you slow down and actually read the code - and I consider myself less-than-great at actually reading other people's code. It took me all of ... 15 minutes to find my way around, figure out the machinery I needed to hijack, and maybe another 45 to get a crude MVP of my concept working.
Honestly I prefer it over reading documentation and then having to mentally map to the codebase. I wish I could write this code well.
You sure you've actually read any of it, or did you just skim, see no docstrings, and decide it's crap?