A few thoughts.
CX does not show on EF.Try QF or Awardnexus. Keep in mind that you can not book with AA miles more than 331 days out.
QF to SYD from NA is difficult in J so look at CX to HKG or SIN.Going onto SYD would be 2 awards (55000 + 35000)in J for a total of 360000 AA miles RT for 2 so you need another 10000 AA miles. You can also look at CX to SIN RT at 220000 miles for 2 and use UR/MR carriers on to SYD.
Check out FT'er Jaminbaker (SP?) as he seems to be the guru for getting to SE Asia on miles. Good luck.