I am watching this thread with interest. In response to the OP's conundrum, would flying on a validation be a way to getting the relevant time on a CS25 aircraft without having to go through the process of converting to a CPL/IR on pistons? And then get your 500 hrs and then do the ATPL skills test? That assumes you have a job offer and the relevant multi-pilot rating could be added to your SA ATPL.
To the second poster Cobalt - I would question your reason for getting an EASA licence if you don't have the right to live and work in Europe. It is a very expensive and time consuming process. You will have to do an approved ground school, pass the 14 ATPL exams, then do a CPL course which based on your total time would be a min of 20 hrs according to the UK CAA, you would do an abridged IR (min 15hrs), and then the MCC course, and I think you would probably need 100hrs PIC to tick the boxes for a CPL issue so that is another 30 hrs. All of this is a very expensive exercise if your future employer doesn't require it. As a french speaker have you thought about looking at operators in West Africa? It might not be everyone's first choice place to live and work, but being fluent in French might help make up for a lack of experience and enable you use your SA (ICAO) licence and gain valuable experience.