In the case where a non-standard region has been set for the primary
system language, the secondary locale will be used for localized
strings when available instead of the expected primary language.
For example, set system locales to [en-SE, ja-JP], that is English
with region Sweden, and Japanese with region Japan, most apps will
display English descriptions but those which have a Japanese
translation will display that instead.
This commit adds a fallback case for when the primary locale has not
matched any translations, but it's language part does.
87d4779c2d