Hi, I'm Pabi

I read the wikipedia article.

Controversy surrounds the origin of the name. There was quite a number of people with the name "Johannes" who were involved in the early history of the city. Among them are the principal clerk attached to the office of the surveyor-general Hendrik Dercksen, Christiaan Johannes Joubert, who was a member of the Volksraad and was Republic's chief of mining. Another was Stephanus Johannes Paulus Kruger (better known as Paul Kruger), president of the South African Republic (ZAR) from 1883 - 1900. Johannes Meyer, the first government official in the area is another possibility.
Precise records for the choice of name were lost. Johannes Rissik and Johannes Joubert were members of a delegation sent to England to attain mining rights for the area. Joubert had a park in the city named after him and Rissik has his name for one of the main streets in the city where the historically important albeit dilapidated Rissik Street Post Office is located.[13][14] The City Hall is also located on Rissik Street.

I understood that. Buy why an African city has a German name?