CASA will deny every qualification they possibly can, to any individual within Australia or outside it.
They are looking for ways to keep you "safe" (that is, permanently grounded). Be afraid; be very afraid... and so on.
Hence the requirement to re-sit the IREX theory exam if you dare to do your instrument flying outside Australia for a couple of years. How dangerous!
However, good news!
The Australian parliament specifically requires CASA to issue you with an Australian instructor rating on presentation of your NZ equivalent rating. Even if you have already undergone the TTMRA for other qualifications, you can always add a new, not-yet-converted, current rating at any time.
But, once the Australian instructor rating has been issued, it must be kept current according to Australian rules. You can't use TTMRA to keep it current.
Therefore, don't convert a rating until you are ready to come over and use it. (Everybody loves New Zealanders over here, so it will be dead easy to find work. Just tell them all about NZ!)