Yeah.. we EXP's do fill up the HKG lounges
Of course CX gets cash from AA every time we do so...
I believe CX Silver gets you access to CX's lounges only- right? Whereas if you hit AA PLT, you'd be OW Sapphire, and get into any of the 10 (soon to be 12) airlines' J lounges.
FYI. In Coach, only Y, B, and M CX fares mean anything on AAdvantage.