I would also point out that being union did not prevent them from being used beyond the scope of the side letter during the AA strike as well. Huge economic issue for all.
As far as I know, the foreign FA's cannot fly anything except to/from the AA international gateways, and would have limited ability to cover any more than
few US to LA flights than they already fly.
They cannot under any circumstances arrive in MIA and fly onward to DFW, PHL or CLT.
Anyone considering that as a big issue for their vote was an abject fool.