[zozbot234]

> The backlog there is pretty insane even while finishing upwards of 150 ebooks per month

Isn't the backlog there mostly in the post-processing step, though? To the point where they're taking finished texts and running them again through the page-by-page proofreading in hope of fishing out more OCR typos and improving the format markup?

You can also contribute at Wikisource if you prefer, that doesn't really have a post-processing step and has much less of a fixed pipeline. (There are explicit "proofreading" and "verification" steps per page, but not much beyond that.)