Sometimes, authors give their take on how their series' title is to be translated, this seems like a case of a "google translation" of the title on part of the author (It's awfully common). "Soredemo" can be translated as "still" or "even so" depending on which is more grammatically correct, "Sekai wa utsukushii" translates to "(the) world is beautiful." Equivalents for some determinatives like "a", "an" or "the" don't exist in Japanese. Actually parsing the title "それでも世界は美しい" through google translate gives "Still the world is beautiful". So my guess is either the author or his editor wanted an official English title... and ended up with that without proper knowledge of English, as I said earlier, it's awfully common, just take a look at the recent anime "Shuumatsu nani Shitemasuka? Isogashii desuka? Sukutte Moratte ii desuka?", the original novel has this Engrish title underneath the title in Japanese "Do you have what THE END? Are you busy? Shall you save XXX?"
EDIT: Realized I didn't give a take on the translation itself, either "Even so, the World is beautiful" and "The World is still beautiful" are proper translations of the title. But the official one is the weirdly worded one because Word of God