It leads to the app being rejected when uploaded to App Store Connect.
The rejection email says:
ITMS-90176: Unrecognized Locale - The locale names used in
localization directories at ('Payload/Mobile.app/Settings.bundle/ca-VALENCIA.lproj')
are invalid. iTunes supports BCP47 but not the UN M.49
specification. Refer to the Language and Locale Designations guide
at https://developer.apple.com/library/content/documentation/MacOSX/Conceptual/BPInternational/LanguageandLocaleIDs/LanguageandLocaleIDs.html
for more information on naming your language-specific directories.
Change-Id: I0ede85c5cc65c203e93ff4b75e898a3faaef20e2
a115168f46