For the record and future updates of this quiz: CBF (Brazilian Football Confederation) has reconized at August 25th the 1937 Champions Tournament as the first Brazilian National League, which Atlético Mineiro has won.
here's a link to the reference about it: https://www.cnnbrasil.com.br/esportes/cbf-reconhece-titulo-brasileiro-do-atletico-mg-em-1937-clube-agora-e-tricampeao/
here's a link to the reference about it: https://www.cnnbrasil.com.br/esportes/cbf-reconhece-titulo-brasileiro-do-atletico-mg-em-1937-clube-agora-e-tricampeao/