I think that the word saudade isn't literally translatable to any language... only in portuguese it isn't a verb.
Longing it's more to desejo, anseio, than to saudade.
I think that the word in portuguese isn't necessarily the first person, but in the english it would be nice... Here we have a pretty tough word to translate, hehe
I really don't see problems with this translation. But in other hand Thatha said there's no first person in the Portuguese sentence.. it would be if it was "Eu tenho saudades do meu irmão"