Actually, the ping on Brazil for the other south americans are way too low compared to NA, and since you said about a MOBA, I tell you something, on DotA2, there is only one server for South America, which is on Brazil, however, you can choose "language preference", which could also easily be implemented on Blade&Soul, like they already do making NA and EU servers separately.
Nonetheless, I think a single server for south americans wouldn't have this big language barrier, after all our languages are very similar and we can understand each other easily.