It seems like without *some* localized file (according to the file properties/inspector in Xcode), overlays like Game Center don't end up showing up as localized when the OS language is set. (Always English, even though the GC app shows up localized when brought up on its own.) So... I added this placeholder file and configured localization on it to get GC, alerts, etc. to show up in the OS's language in-game. Added French, German, Spanish, and Italian.