If I went to live in FRANCE for a couple years and came back with a thick ass French accent, yes people would think I was fucking retarded and faking it.
You can go to a foreign ENGLISH speaking country and pick up a slight accent after many many years of living there. But NO, you can't pick up a very specific foreign accent from living in a country where they DON'T speak English after a couple years of living there.
And OP, you're wrong. English is her first language , although she now states she feels as though Portuguese today is her first language. While you are correct that she has spent a lot of time the last couple years with Brazilian people, she spent a lot of time speaking Portuguese with them, not ENGLISH.