AS1554 isn’t just a one weld one material type code. If you change materials, position, thickness of material etc, you will need to qualify to weld to these parameters in the PQR to get the WQR.
If you were using AS 4041 it would be true as butts qualify the welder for fillets also
You can’t just enroll for AS1796 pressure tickets without proven prior experience. They don’t run these courses to learn on, they run them for experienced welders wanting further qualifications