Wikidata modeling for books is quite non trivial, there is a distinction between the "underlying work" and its "editions and translations" that adds complexity for typical use, and isn't even totally clear at times (e.g. is X an "edition/translation" or a new creative work that's merely "based" on a previous one? It depends - different people can answer the question differently! Is manifestation A the "same edition" as manifestation B?). Even Wikisource.org, which is a Wiki project, hasn't managed a comprehensive integration with Wikidata as of yet!
Regardless, the OP is doing some great editorial and curation work, and this is something that many other ebook resources don't have. It's great stuff.
Agreed, it's incomplete and imperfect, but I still think that it would be a good addition. And I also definitely agree that the OP does great work, I bought the full collection just before writing my last comment.
Regardless, the OP is doing some great editorial and curation work, and this is something that many other ebook resources don't have. It's great stuff.