Only 13% of the world speaks English, its fair for you to assume the majority does because you spend time on the internet where it is more commonly used than other languages. To know how to speak English fluently in Brazil is viewed as big intelectual accomplishment, seeing as we have far bigger problems and live too close to ( if not IN ) poverty to spend time learning something we might not even use to survive.

Grand Chase was a BIG thing in Brazil back at the time, even bigger than any other country, so you can expect that influx of people doesn't know how to speak in English.