I don't usually rely on downloaded metadata for Published date. I tend to use the FantasticFiction website and have set
Prefs - Look&Feel - Default author link template to
Code:
http://www.fantasticfiction.co.uk/search/?searchfor=author&keywords={author}
so that when I click on the author name in the Book Details panel it takes me to the relevant webpage. Also useful for getting book series info. But I manually enter the data into calibre.