Yeah, like what Natrium said, its better if you just let the user pick which language they prefer, rather than auto forced it.
I travel a lot, I would be pretty pissed if a game I played in English, keep changing to other language every time I'm in a different country.
Maybe you can make a pop-up that says, for example : "The game is currently in English (default). Do you want to change it to Portuguese?" [Yes] [No] , on the game first launch.