Read the base language

pom_translate_get_base_language(): string returns the configured source locale. If no POM Translate value is stored, it falls back to the site's WPLANG option and finally en_US.

$source_locale = function_exists( 'pom_translate_get_base_language' )
    ? pom_translate_get_base_language()
    : get_locale();

The base language identifies source content; it does not by itself tell you whether the base URL uses a prefix. Use pom_translate_locale_uses_prefix() or the localized URL helper for routing decisions.

Do not compare only the first two characters when regional locales are configured. pt_BR and pt_PT, for example, are distinct locale values.

On multisite, call the helper after switching to the intended blog. Its memoization is scoped to the active site and current settings context.