CNN — A fortnight ago, Motswedi Modiba was a South African singer showing signs of a promising career in her home country. Now she’s a breakout hit on one of China’s largest reality TV shows after wowing millions with her performance in Mandarin. Modiba, reported to be the first Black and African contestant on “Sing! China,” impressed the judges with her cover of the ballad “Love” by Karen Mok. The competition, in its eighth season, follows a similar format to “The Voice” in the US, with the first round judged blind. Two of the four judges selected Modiba to progress…