I don't think the SADF was ever a "force to be reckoned with".
Apartheid SA weren't very successful as far as I'm concerned.
They fought a protracted border war and the outcome was a complete loss of their original objectives.
At best the propaganda machine was hard at work back then convincing the safers of the time of how successful, incredible, etc. everyone involved was.
Realistically wars are incredible expensive, not just financially, in every respect, so if the outcomes are divisive, an enormous blunder was made.
It is exactly why the US is criticized for every conflict since WW2, especially Vietnam and Afghanistan.