Unfortunately I think you have to change it because the joke is that the main character doesn't understand the insult at all, I think he suspects he's being insulted but he doesn't understand it perfectly.
MissFortune was looking for the same thing with a player who only understands English, so if the game is in Portuguese, that dialogue has to have an insult in another language.
But if you leave it as it is, it is fine too
. In my case, I don't speak Portuguese, but I speak Spanish very well, and as you know the languages are quite similar (89% coincidence), so by deduction I understood the phrase and the insult without looking for a translation
.