Well I'm still an expat, going on 12 years in the Middle East now and likely to finish my career over here...unless I finish up as a little old man gone back to flight instructing!
But...a couple friends of mine have gone back to fly at home. They had to have their logbooks stamped and certified by flight ops at this company, and they kept copies of their last several PPC's (all of them would be better if you have still have them or can get them). This verified their experience to TC's satisfaction.
Neither of them had kept up their Canadian medical (nor have I for that matter) but once they did it back home and had their above mentioned documents vetted their ATPL's were reissued with no written exam required. They may have had to do one PPC in Canada, I'm not sure. From what I understand it's much easier than renewing your Canadian Driver's license!
I know what you mean about authorities trusting African operations though. Best of luck.