The purpose of categories is to group things of the same type together. Real things with real things. Fictional things with fictional things. Mixing real things and fictional things is a misuse of categories. A real book is not and can never be a fictional library or a fictional librarian. 
 The category about cities in England is irrelevant, beyond the fact that things that are not cities in England shouldn't be categorized as cities in England. 
 It's not at all difficult to maintain a category for fictional things. Just don't add real things to it and if real things are added to it, remove them. 
 But what the fuck ever. Tyranny of the minority is the rule of law on Wikipedia and ultimately you're going to re-add these categories regardless of how wrong and illogical it is. So have at it. Categorize real books as fictional libraries. Knock yourself out.