For the EPUBs in
Free eBooks-de/de, I started
a tool to automatically download and epubcheck them, unfortunately their technical quality
isn't quite as good as the proofreading is claimed to be. Now some users started to correct their uploads manually, maybe we might even try to automatically fix them. This makes me wonder if the English EPUBs could need a similar technical check, either by you guys or, if you have a public list of them like the Wiki list, via automated download and epubcheck. If you have any questions or need a translation of the thread I've linked, just feel free to ask.
In theory, more could be done with a library of valid EPUBs, but as they're not all in the Public Domain and the legal state per book is unknown, it's way too risky to work with them except in private (which I would consider as a waste of time, as other people would want or need such results as well).
Could you please prominently sticky post a link to the origins and history of the Patricia Clark Memorial Library? I was unable to find it, but maybe I have just overlooked it.