So Maybe "sweet talking" is not so good but there is a case to be made for "talking sweetly".

I also felt like a caveman compared to the Brazilian politeness.

However, I get it. Sometimes there is politeness in front of your face and there is backstabbing behind.

A lot of politeness is telegraphing intentions to strangers. Initial contacts with others have to result in exaggerated gestures until contact is established

Perhaps as they become friends there is more directness.