Also just to add in my experience, if you are fit and have a luggage cart or rolling luggage, it seems faster to me to just walk/run down along the connecting walkways between International and AAs T2D as opposed to taking the Airport Train. You go past all the UA check-in areas then come to AA check-in at the end of the long concourse.

You didn't mention if you are traveling all on one ticket or separate tickets. If on one ticket, then you will be protected though it would be interesting to hear that you were booked with an illegal connection (according to CX guidelines stated here). If you are on two tickets, I'd look into changing the AA portion to something later if you can.

AA Security at SFO has elite/premium line so if you were able to re-check bags in International and already rec'd. your AA BP prior to CX flight, that would make a big difference. The distance from AA Security to the AA gates is pretty short, from literally 30 seconds walk to maybe 2 minutes.