Well, I don't think you'll see Terre Blanche becoming prominent. TTL Fascism vehemently rejects antisemitism, so any South African politician is most likely screwed if they start complaining about "Zionist interference."
While South Africa has sacrificed the veneer of democracy it once had, I think the Afrikaner extremists have enough self-awareness to try and not emulate the blackshirts. Remember, they want to attract mostly skilled European immigrants. Acting like militarist nutcases is really bad PR, especially when there are a lot less controversial locations to immigrate too, like Canada, America, Australia, and or even Katanga if you want.
As time goes on, settling in Southern Africa will be one of the things that is frowned upon, like misogyny and racist jokes. Looking respectable is the only way South Africa can keep the immigration flowing.
Yeah but from what I read, South Africa TTL is essentially crapsack. They already don't seem to have the best reputation, and adding paramilitary elements won't really harm that. After all, business flourishes today in China, and Hun Sen's cambodia, with foreigners emigrating there. Some people just don't care, and anyone who's opinions WILL get swayed will probably already be turned off by the human rights abuses already. Also, the prevalence of Fascism has normalized paramilitary units probably. South Africa doesn't need to look respectable when it has been made pretty clear this South Africa is already much worse than OTL. As phased by
@Sorairo , while the other white dominated nations have some sort of loopholes where it is theoretically possible to get a semi decent live as a non white, the attitude of TTL South Africa is "what is a human right?"
In terms of less controversial places, I do not think anyone who plans to go to those countries you mentioned ever planned to go toTTL South Africa. It is pretty safe to say people will emigrate to TTL south africa because their home countries are too "liberal" "marxist" "satanic" or "communist." Probably a lot of disillusioned racists in the American South during the civil rights movement, exiled British fascists who are disgraced at home, probably French Far Right that will be pissed about whatever happens in Algeria, potentially future Iron Curtain political refugees.
Remember, South Africa has already received the middle finger from the entire liberal world. As has Rhodesia, but as the author said, TTL Rhodesia isn't as bad as TTL South Africa still. Given the diplomatic crisis, any liberal westerner is probably going to dislike South Africa/Rhodesia from the start, while the Far Right will view it as a heaven for their self imposed exile.
South Africa already joined the Rome Bloc, so regardless of aesthetics it is already a Fascist State. They might as well try and fully integrate with their patrons, since their PR amount any western liberal is fucked anyway.