Yes, that is how the process begins. After the Bro's are served the Foreign Judgement by the Central Authority aka the Superior Court they can challenge the Judgement. This is not about the U.S. merits, it's about whether it offends Brazil Law. This action triggers the creation of a court case. This is where the Court can set the Judgement aside.
There is no Convention on Recognition or Enforcement in Brazil. It's their way or the highway.