i am planning a xONE5 ex HKG starting in January. I wanna do HKG-CTS-KIX-CNS-AYQ-SYD-SCL... the KIX-CNS is operated by Jetstar (QF242). My agent told me that Jetstar flight is not allowed. Is it true?

If it's not allowed, how can i go to any australian city from KIX or CTS? Since i start my journey from HKG, it seems i can't return HKG to transit... and HKG-CTS-KIX has effectively used up my 2 sectors available for Asia?