Yeah the literary rate probably plummeted rock bottom compared to the pre-regression age. There's probably a popular theme about man growing decedent and being punished by god with loss of their ancient wonders in some of the more current stories. A lot of scientific knowledge has probably either been forgotten or warped into semi mystical pseudoknowledge (looking at you eco-buddhists). There might be "some" preserved records from the pre regression age, gathering dust in a nondemoninational, scientologist or mormom library. Mad Alchemists who wish to harness the power of the Ancients to unleash horrific destruction upon their foes is probably a popular theme of in universe stories.