Are we talking mostly about the language chooser on the login screen here ?
Also, we are more or less tied by the set of locales that are shipped in glibc. There are /usr/share/i18n/locales/ar_AE /usr/share/i18n/locales/ar_BH /usr/share/i18n/locales/ar_DZ /usr/share/i18n/locales/ar_EG /usr/share/i18n/locales/ar_IN /usr/share/i18n/locales/ar_IQ /usr/share/i18n/locales/ar_JO /usr/share/i18n/locales/ar_KW /usr/share/i18n/locales/ar_LB /usr/share/i18n/locales/ar_LY /usr/share/i18n/locales/ar_MA /usr/share/i18n/locales/ar_OM /usr/share/i18n/locales/ar_QA /usr/share/i18n/locales/ar_SA /usr/share/i18n/locales/ar_SD /usr/share/i18n/locales/ar_SY /usr/share/i18n/locales/ar_TN /usr/share/i18n/locales/ar_YE but no ara locales at all. How would ara be mapped to one of the ar locales ?