Well, here's how I see it. Your HKG-JFK sector is fine, but good luck getting CX to allocate A space on the non-stop. Best bet is to waitlist, then hope for a day of departure clearance. JNB-xLHR-NRT is OK, but remember that only one transit through LHR is permitted. With regard to North America transcon flights, only the city pairs specifically enumerated in the rule are prohibited, and I don't think that SDQ is on the list, so you should be OK.