The main reason why Brazilian modernism can seem more natural and warmer and welcoming compared to American or European modernism is because Brazil was because Brazil was behind the US/EU in terms of industrial/technological development.
Modernist designers elsewhere were exploring new manufacturing techniques and materials like concrete, fiberglass, metal, etc. while in Brazil they tended to use more traditional materials and construction.
So for example a modernist designer somewhere else might design a chair that is distilled down to the essence of what it means to be a chair and nothing else, and molded out of a single piece of fiberglass in some factory somewhere. But in Brazil, they would still explore the same ideas like a chair stripped down to its core function without excess ornamentation, but the chair would be made out of wood and leather by a traditional chair making craftsman using mostly traditional techniques.