Ask HN: How to Measure the Comprehensibility of a Codebase?

I was recently working on a codebase that was probably the most incomprehensible I've ever worked with: build files call shell scripts which call python scripts which call Ansible scripts. Very hard to trace where one repository's responsibility started and another ended. No logging whatsoever except for a few "print" statements. It can't even be made to run locally!

This made me think: are there ways to quantifiably measure how "understandable" or "comprehensible" or "easy to learn" a codebase is? I feel this should have been studied in some way already since having a well-defined codebase enables easier onboarding of developers.