I met the plugin Transposh for WordPress that translates Posts and pages using Google translation tools and Bing and edit translations. He is totally excellent. However, He brought me a problem with the language of the Admin. Left all of it in English rather than the language that I wanted. This is not actually a bug but a behavior due to him not having my default language set that is the Portuguese of Brazil and the Portuguese of Portugal.
To resolve this problem, vá até os ajustes do plugin em Transposh -> Settings (in the side menu of WordPress left will be the option of Transposh) and uncheck the option in Enable override for default locale of overwrite default location and WP_LANG (see screenshot below).
Will notice the change soon when saving.
Hugs and I hope I have contributed.