How does the CCP insure fair ethnic representation within the CCP?
Representation at the Party Congress itself will not mean much in terms of actual authority. It remains to be seen how many and which Tibetans find a place in the Central Committee, one of the three top decision-making bodies in China’s political system. The Politburo is the second, and its Standing Committee is the most powerful. To date, no Tibetan has found a place in either of these two higher levels of party leadership, despite China illegally occupying Tibet for over 60 years.
https://savetibet.org/38-tibetan-delegates-at-chinas-20th-party-congress/
Reading the article, it seems there's not much effort made to increase the representation of Chinese minority groups within the CCP, and I couldn't find anything on the Internet that suggests otherwise, but maybe I am wrong. I know there's affirmative action in hiring, education and family planning, but not in the hiring of government officials.