It actually brings me back to Umberto Eco's The Name of the Rose. Spoilers for a 30 year old movie and 40 year old book, but the main conflict arises from the discovery of the (fictional) second part of Aristotle's Poetics: Comedy. The Poetics was a book ABOUT writing, basically it was literary theory from way back in 330 BCE.

As mentioned by Lyth, the difference between "Comedy" and "Tragedy" wasn't so much "one is funny" and "one is sad", classically they were just "this one has a happy ending" and "this one has a sad ending" (note: this is also why Dante's poem is named the Divine Comedy, it doesn't have a sad ending, and Dante never called it that himself, but it was later named such because it has a happy ending. Hell, originally it was just named "Commedia" until Bocaccio added the "Divine" part late in the 15th century! And it was solely named "Comedy" because it wasn't a tragedy! /rant)

So basically, my interpretation is that the tomestones aren't compilations of jokes: but instead treatises into what makes an Allagan literary work a comedy.