I work for a company that creates apps for the Japanese iOS App Store. Our only supported language is Japanese.
We selected Japanese as the "default language" in iTunes Connect, but when our apps appear on the App Store, they have the problem shown in the screenshot (the language is listed as English).
It's been suggested to me that setting the CFBundleDevelopmentRegion in info.plist will solve this, however I can find no mention anywhere in Apple's documentation about what format the language/region string should take. There are numerous standards, several of which are supported randomly by iOS in different places (JP, JA, JPN, JAPAN, JAPANESE etc.) and I've not been able to find an authoritative answer by googling. We think this may be correct
<key>CFBundleDevelopmentRegion</key>
<string>Japanese</string>
but would appreciate it if someone could confirm or suggest a better answer, as we don't want to go through a trial and error process, given that app store approval takes a week to get a result for each attempt.
Please note: This is not a localization question. We don't want to support additional languages. We just want to set the base language to Japanese so that the app is correctly displayed in the store.