That's pretty much the entire question. South Africa and Cuba were both directly involved in the Namibia/Angola conflict, and it is conceivable that their forces may have met in battle.
If so, how did it go? Who won? What was international reaction?
Thanks.
South African and Cuban forces did indeed fight in Angola. In fact, Cuban forces were instrumental in halting and eventually reversing the South African advance. The entire encounter was a public relations nightmare for Pretoria. Consider that in the early stages of the South African invasion, Pretoria did not even acknowledge that it had sent its troops into Angola. ("What? The MPLA and Cubans have captured white troops? They must be mercenaries!"). The press across Africa had a field day. Consider the implications of black forces defeating white armies. It was an enormous PR victory for the Cuban-MPLA axis.
Chapter fourteen of Piero Gleijeses' Conflicting Missions has details on the October, 1975 to March, 1976 fighting (when the South Africans withdrew).