LANGIDs have some unusual quirks that can cause trouble. Its generally best to avoid language specific assumptions. If absolutely necessary, consider using resource loading to load appropriate resources, or use that locale name (ie: en-US) or rfc GetLocaleInfoEx() properties to provide information

This doesn't work for custom locales

Custom locales all have the same langid, sublangid, etc. so LCIDs and their derived parts are pretty useless for describing locales accurately. en-FJ, fj-FJ and klingon would all have the same LCID/langid/sublangid.

Use locale names (en-US, etc) insteadl.