A few more ideas to use the segments / miles:

In Africa you could go to SEZ and then SEZ-Nairobi-JNB-CPT-JNB on BA

Or you could try to go back thru Europe (not sure if it is still allowed) without stop, so CPT-xLHR-HKG (or somewhere else in Asia)

In Asia you could add a few flights from HK (India, Bali, Japan....). Also you could take QF from some other airport than HKG (BKK, NRT, SIN...)

In Australia you could add a few segments to PER (long) or other places.

Also you could try to add Dubai either at the beginning or the end (then you would need to do LAX-LHR-Dubai-LAX-DUB.

Have fun!