I haven't read "Cora Unashamed," but I have read and taught "Sweat." The latter story seems less concerned with racial prejudice and racial stereotypes than it is with conflict within marriages, or between the sexes. Even that assessment, however, is a bit of an over-generalization, since the story in fact seems to deal with two highly individualized people, neither of whom seems to represent much beyond himself or herself. This, in fact, is one of the qualities that helps make Hurston (in my opinion) a very talented writer. Her characters are not merely two dimensional.
I think, however, that they are somewhat more two-dimensional in "Sweat" than in "The Gilded Six-Bits," which is one of the best stories I have ever read. The husband and wife in that story (especially the husband) are extremely complex characters. That story, by the way, also seems more relevant to racial issues (especially in its opening and closing pages) than does "Sweat."