As an AA EXP travelling internationally on oneworld you should have been allowed Emerald access.
https://www.oneworld.com/ffp/lounge-...access/SFO/906
Of course, CX are very protective of their lounge - they mey see AAdvantage and just say an automatic NO!
Did you try the China Airlines Dynasty Lounge ?
https://www.oneworld.com/ffp/lounge-...access/SFO/832
If, so, what was it like?