Is a simple transliteration enough for the whole pic to be marked as translated ? Romaji or not, it's still japanese...
Given the lack of official translation (that I could find), the idea is that non-speakers are easily able to match the romanization to the tag name on the left, instead of them having to look at the alternative names on the copyright's wiki, in order to see that it's simply the novel's title. If deemed necessary or helpful, unofficial translations could be added to the wiki.
As for the author, illustrator and publisher names, these are what english speakers would find them by too (see the publisher's Wikipedia for example), so there's not much else to do here.
Illustrations: Chigusa MinoriHozumi Kei
AuthorOnii-chan to no Honko no Koi nanteDarenimo Barecha Dameda yo ne?GA Bunko
Publisher