Hello,
I miss the opportunity to have more than one field for a title. I suppose it would be good to have one title name in your native language and one in original language.
As for series, there are books that technically belong to more than one series. As an example we have a publisher who prints scifi books and calls them "best scifi ...." and numbers those books. And some of those books have their original series, like Isaac's Asimov's "Robot". And there is a need to track both series.