Maybe it’s the KUL ATC that needs to look closely at their level of English and how they use it with native English speakers. Deviation from standard ICAO RT and you are asking for trouble. That goes for pilots and ATC. I’ve been in there more times than I can count and the standards of ATC leave a lot to be desired.
Maybe it was CX crew that's having trouble understanding ATC on that given day. I have flown many times into Australia and many times the standard of AUS ATC has a room for an improvements.
