Translation:I will have gotten to know Brazil in 2014.
From the Portuguese sentence, that seems ok to me. (Unless there is something weird with the English sentence).
Terei conhecido is literally "I will have known". In fact, we use "conhecer" as something deeper than just being there.
Terei estado is literally "I will have been", which in Portuguese is just being present there.
And once again, it's just about english "known" and English as an "intermediário entre as duas línguas"!)))))) For me "conhecer", concerning a country, is also something more, like to meet the culture of a country, its people, nature and so on! But the question is why "I will" is accepted and "I'll" is not!))
"I will have known Brazil in 2014" sounds truly strange to me. Even Duolingo's current translation "I will have been to Brazil in 2014" sounds odd, although less so with "in" replaced by "by". Can you find another form of words to explain what the Portuguese sentence is trying to say?
That may work for American English ("gotten" is not used in British English except in some set phrases). Even with that, "I will have gotten to know Brazil in 2014" sounds like a mix between "I will get to know Brazil in 2014" and "I will have gotten to know Brazil by 2014" (assuming 2014 is in the future). I'm probably missing something.