@mmat1
To make my theme more clear, please have a look to a screenshot I took from the translation program "Qt Linguist":
Screenshot of "Qt Linguist"
It's only a small extract of the 454 entries in the section "Metadata".
Are you aware of all these 227 categories?
From my point of view none of the entries of the screenshot is related to books or ebooks. These entries are typical for movie business.
Only a subset of few categories in the Metadata section makes sense in an ebook.
We all know the multiple and annoying kinds of categories from the end credits of movies.
But, in book business, these categories are not in use.
For example "woodcutter". No one in book business uses this category. Typical for book business is the category "illustrator". No one cares about the technique an illustrator uses. But the category "illustrator" is not part of the core. Therefore it makes sense to provide "illustrator" as additional field, but not "woodcutter".
I showed the screenshot to my girl friend. She is involved in book business for a long time. Her answer was: "It looks like an alien speech."
Only few categories of metadata are in use in book business. Most of them are described in the core. But some other additional categories make sense. The challenge is, to identify these categories and to shorten the long list to an appropriate subset.
I highly recommend to do so. Even if it's not easy. I would appreciate to support this action.