Adding Custom Language Codes to Sitecore
You can also add custom language codes into Sitecore by editing the Website/bin/CTAddedLanguageCodes.xml file. However you must also contact Clay Tablet and your translation provider to ensure the custom languages are set up appropriately in the Clay Tablet Provider Connector as well as in the Translation Management systems.
Note: If your company sends content to your translation provider via the Clay Tablet FTP Connector on the translation side, it is not necessary to contact Clay Tablet, because the FTP Connector automatically creates folders based on the job name and language pairs, even for a custom language pair. However, you must inform your translation provider about the standard language code into which to translate the content.