I find it hard to understand what can be meant by ‘mestiço (mixed-race) art’.
No one disputes that the Brazilian people are of mixed race, but even if this is the case, the idea that their artistic creations should also be ‘mestiço’ seems to be an argument that may be logical but is unverifiable in practice.
The first difficulty is that I can see no causal relationship between an individual's racial make-up and the character of the object he or she produces or creates. In my view human individuals are essentially cultural. So it is on the cultural level that they are defined and their creations described. From this it can be concluded that if a mulatto transmits something of his mulatice (‘mulatto-ness’) to his art, this has nothing to do with the type of blood flowing in his veins, but is related to the influence that his position as a mulatto has on his world view, if indeed he has one. Personally I can see no sign of it in the work of Machado de Assis, for example. Should writers' social and racial position influence their work? Of course. But not to the extent that it becomes visible and less still so that it determines the quality or meaning of the work.