With regards to that SWA cable, the same construction is used for 11kV, 33kV and 66kV cables, with only a small increase in the number of overlapped oiled paper insulating sleeve windings used. They do have a very robust overload capability, in that you can have the cable running for decades with the temperature at the melting point of the pitch pour in the seal, provided that your cable ends do not get wet during this time.
I regularly see these in excavations, still powered, and with the pitch covering mostly gone, leaving the steel tapes exposed and corroding away, but the lead keeps it in more or less working condition, till it cracks and lets water in. Then the cable can and will excavate itself, I saw a failed 66kV joint, that blew itself out of the ground, leaving a 6m deep hole where the cable was buried, and turning the cast joint box into an art object. Current practise is not to lead wipe the joints, more due to the lack of any training on the art of lead wiping, and the older experienced people having mostly retired. Instead they use a cast resin joint, generally taking the paper cable to a PVC or HDPE insulated cable for further use, as it is something the electricians are trained to work with, though the core then changes from copper to aluminium in higher current uses, unless the length is short.
As to RCD units, the type with a ground connection was used for a few years here, as the earth connection allowed the unit to detect the loss of supply neutral, tripping on loss of neutral using a 120VAC MOV device, and also incorporating a 480VAC MOV from line to earth as well, which meant you had to disconnect the outputs before doing insulation tests, and you could not back feed them.. the current approved types are smaller, and are strictly 2 wires in and out, and are strictly 30mA RCD, requiring external overload protection. Required on all socket outlets, so typically, as it is rated for use as a disconnector, it is the single main input breaker, so if it trips you are in darkness.
Thankfully with the current Eishkom issues everybody has at ready reach some torches, a cellphone with torch or some form of lighting, as you will have regular rotational load shedding, and you might not get power back for a few hours to a few days if the bit turn on surge into a very cold load kills something upstream.