Given the history of both South Africa and the former Yugoslavia, I'm not exactly shocked. South African industry has had mixed results when trying to build safe, reliable firearms, and the former Yugoslavia has and will sell to pretty much anyone.
The RSA under the Apartheid Era was very successful in building firearms. As a western aligned capitalist nation, they never purchased arms from Communist Yugoslavia. In fact, the RSA fought Communists in Southwest Africa, Angola, and Mozambique. They even fought Communist Cuba in Angola.
Due to the embargo placed on them for supporting Apartheid, they developed a native production industry of gun government owned gun companies. They built an excellent metric FAL known as the R1, had their domestic commercial production guns under the Musgrave line which included a clone of a Beretta pump shotgun and a successful series of hunting rifles.
Later, they established their own Galil line along with producing the excellent clone of the Beretta 92FS that they reverse engineered. It was so good, Beretta instead of suing them, licensed them to produce it under royalty. The Vektor Z88 is an excellent pistol.
For foreign contracts, the RSA used Israeli, German, and Spanish arms, not Yugoslavian guns. Spain and Israeli, being western aligned anti-communist pariah states themselves. They have close relations with the RSA. West Germany, also supported the RSA due to former German settlers living in Southwest Africa, which at the time was part of the RSA.
The Star Bonifacio Echeverria Model BM from Spain was issued by the SADF during the Border War and it smoke checked a number of SWAPO and Cubans in Angola.
The SAP issued the Walther P1 (post-war aluminum frame P38) as their standard issue duty gun and used them to great effect against uMkhonto we Sizwe.
They also domestically produced the Milkor BXP SMG and Milkor MGL.
I can see the current production Serbian M57 Tok as a popular pistol in the rest of Africa because they're cheap and 7.62x25mm Tok being common in those areas due to those countries formerly being supplied by the Communist Bloc.
The Horn of Africa had the Derg in Ethiopia and the Jamhuuriyadda in Somalia. Both were Communist Bloc client states. Plus you had Libya supplying arms too and they were a Soviet client state.
