HC that there are really 4 types of human cultures within T’au Empire controlled space.
The first are border territory. Near the Imperium you find it mostly similar to Imperial culture and uneasy. The T’au use Water Caste both to do limited trade with the Imperium and slowly bleed the Greater Good into the working class of these border territories. Humans who accept the GG are often moved out of this territory for their own protection. Most accept the GG or try to move deeper into Imperial Space lest they get caught up in a war. Areas are often impoverished because of the Imperial inefficiency, the Water Caste is trying to fix that.
The second are either areas largely human with T’au and non-human auxiliary presence weak. These are often territories not near border that were accepted into the Greater Good with less issue. It is almost paradise by human standards. Access to ever expanding T’au tech, without the pressures of the Caste systems or the Imperial Jack Boot ever down on your head. No nobility, just democracy. Food is your standard Imperial stuff, though higher quality because of T’au tech and no nobility hoarding stuff.
The third are mix of T’au and Human cultures. Here, humans while not fully adopted the caste system, emulate it somewhat for ease of integration. You often find this near the border territories, recently assimilated places. Humans largely either contribute to science, war or bureaucracy. All ways on alert because of these territories often closeness to the Imperial border. Food is bland though will fill you up.
The forth are areas deeper in the Empire or at least farther from the Imperial border, and have a larger Auxiliary presence. These are melting pots of vastly different cultures, often with little control by T’au directly. Here humans are equals among many different races. Food is AMAZING provided you are willing to try stuff, and the exchange of ideas/tech is fascinating.