i was wondering the same thing some times ago, so i wrote to ps support in 2018.
What they told me is that you cannot and shouldn't change region. Region is meant for age control and that kind of stuff, playstation choose to have games bounded to account region rather than have a wider regions compatibility. Your south african games are "bounded" to south african region. You should keep buying south african games, digital copies perhaps, cumbersome indeed. If you buy a portugese game for your south african account, you will be able to play but you won't be able to get any updates or DLCs.
As i said this is what has been told to be back in 2018.