In reality, they're paper alternates that airlines will file on a daily basis as a regulatory required alternate aerodrome. So when last minute or unforeseen delays occur (thunderstorms, fog, excessive holding times) you'll find they will divert to Macau and Shenzhen. When the airlines have more notice (e.g. Typhoons, airport closure or runway maintenance) then they will file different alternates (e.g. TPE for North America, MNL for Aus/NZ/EUR or BKK Mid East/JNB) which have CX ground handling facilities for the expected disruption.