Apple Watch base localisation shows wrong default language

Question

I have an app localised in three languages (Simplified Chinese, French and Czech) with English as the development language.

While the localisations work perfectly on the iPhone, there is an issue with the Apple Watch: If a user has set the Watch language in any other language than English/French/Chinese/Czech, then the content is shown in Chinese instead of English (that should be the default).

According to this Technical Note:

If none of the user’s preferred languages are supported by your app, iOS chooses the language matching your app's development region (CFBundleDevelopmentRegion).

Note: Be sure to set CFBundleDevelopmentRegion for your app. If you adopt Base Localization, make sure that the value of CFBundleDevelopmentRegion matches the language used by your content in the Base.lproj folder.

I have confirmed both the above requirements are being satisfied (CFBundleDevelopmentRegion="en" and all Base.lproj files are indeed in English). Is there something I'm missing? Again, this happens only for the Watch app and not for the iPhone one.

Answer 1

From https://developer.apple.com/library/content/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html#//apple_ref/doc/uid/20001431-130430 , CFBundleDevelopmentRegion is the language and region, e.g. en-US, not just en.