Actually it is the other way. If whites representing 20 percent of the population at best did not colonize the country and treat the remaining 80 percent as second class citizens problems like this will not happen. Do the whites expect all the blacks in South Africa to just forget? This is why our founding fathers were wise about foreign entanglement. Colonizing other nations and treating its inhabitants as second citizens will have blowback. US had empire in late 19th Century (after our elites succumb to the European model of empire), Philippines, Cuba, Hawaii and PR. At least Cuba and Philippines was granted independence after WW2. Despite our short rule over them, we still incur some degree of resentment of our rule over them. Imagine the Europeans who held their colones for a century or more. Hawaii and PR assimilated into the US reasonably well but their are still some residue of blowback.
WTH are you talking about? When the Dutch started settling the south of Africa in the 17th century there was no one there! The first conflicts arose with the Xhosa people who migrated in from the north-east.
Blacks don't have any prior rights to South Africa.
Or, if you are going to take over a territory, as the British colonists did to America, be sure to not leave alive too many of the original inhabitants.
It's not a "legacy of colonialism", or a "legacy of slavery". Black immigrants to the UK (where THEY are the "colonizers") have high crime rates there.
It will get sorted out eventually. Chinese firms are having an increasing presence in Africa. They need African minerals. They do not, however, need the Africans, and can be relied upon to protect their own people and investments, with little regard for world opinion.