I hope you get a reply - even if just PM as info from any gaijin actually there seems non existant.
It might be called Jetstar but it they do things their own old JAL ways - and allowed to by Jetstar head management which doesn't say much about porn* management.
They have openly indicated they do not want gaijin pilots and only go through the charade of gaijin screening because forced to.
Along the same lines a gaijin upgrade - interesting western thought!
Things may have changed.
For interest a number of Japanese F/O's have left the chosen land - and J*J - and gone to J*P, a couple (maybe more by now) have been upgraded to Captain.
Good luck.