(An aside: perhaps a new thread is better since Podcast app workarounds aren't related to the API.)
I've had lots of problems with the Podcast app for audiobooks, and am not sure how to influence Apple to fix them. If one optimistically assumes that someone at Apple will eventually notice, then the best thing to do is document the issues in a way that's simple for a developer to understand, with step-by-step notes and screenshots of what's wrong, and perhaps a simple mockup of suggested fixes.
In this case, a developer might download a bunch of LibriVox books and not see a problem -- since many books include the chp number in the chp title. So, here's one example from my recent playlist that lacks numbers:
(read wonderfully by MaryAnn)
But, it's not clear whether automatic section numbers are useful for podcasts, so this feature may not be an easy sell to Apple. (Or, if I'm wrong and it's equally good for podcasts, a 'pitch' to Apple should perhaps include some examples there too.)
Podcasts and books often have different needs. My own alternative: release an app aimed at audiobooks. The first version is done (free and with no ads); just waiting for the app store review process... Meanwhile there are several other apps (some free; some paid) that are book-centric rather than podcast-centric.