Assuming you are right and half the RAN flying was useful, and assuming all the RNZAF flying was useful wouldn't that give 25% of flying hours being non productive?The aircraft in Australia did about half their flying in support of the RAN, and about half of that was useful for the RNZAF. The RAAF cannot afford to waste 50% of 6 Hornet's flying hours on non productive flying.
Anyway since the RAAF doesn't want to waste flying hours helping other services train that suggests that RNZAF A-4K's flying off HMAS ex-Foch is more of a possibility in a training Carrier scenario. In the unlikely event.
So in a POD where sending personnel to train is not an option, such as the USA going isolationist and pulling back to Hawaii, and China going more expansionist and pushing harder at getting it's own carriers. Buying an old Carrier to train on while your new one is being built would be an option. Actually I'm leaning towards a mixed model where some RAN personnel are attached to the French Navy, while at the same time the Foch is used as a training carrier with attached French Naval personnel.Yup. If you need to reestablish a fixed wing carrier capability, about your only viable option is to send your Aviators to someone who already has one. Or spend a decade plus developing it yourself like China.