Could you perhaps try if adding
bra,pob as "Default subtitle language" makes a difference?
(under: rightclick > Options > Preferences > Subtitles [Subtitle properties])
N.B.:
At this option at the bottom of the "middle column" don't click on [...] as that will lead you the ISO639-2 code page, in which these codes are not present (or indicate a different language), but instead write
bra,pob,por directly into the writable box. (After that don't click on [...] as then the additions made will be removed.)
I don't know if it may work, but I don't know the exact differences between Brazilian Portuguese and European Portuguese either, so I'm unable to really test.