FWIW, this is true of all of Emacs outside of the "core" that has the most users. It's written in C and the parts that only have a few maintainers don't get read very often. The result is flakiness.
(I spent a lot of time reading the font/face handling code to make eslide auto-resize text. I couldn't figure out how to do it cleanly, as the API did not work as documented or coded (!). Eventually I hacked around it, and my hack works fine. Welcome to Emacs Lisp programming...)
