You can add any language that is either already included in Ubersmith or has been added (see Translating Ubersmith) in order to translate your interface. The following translations are included with Ubersmith by default: American (en_US) and United Kingdom English (en_GB), Argentinian Spanish (es_AR), (French Canadian (fr_CA), Portuguese (pt_PT), Swedish (sv_SE), and Traditional Chinese (zh_TW) and Simplified Chinese (zh_CN).
Note: If you want to use a language other than the default ones provided by Ubersmith, you must configure your Ubersmith instance with specific locales before you can translate your interface. See Translating the Ubersmith Interface for more information.