A political decision if ever there where one, the Hunter is neither "Proven" (One of the main criteria for consideration) nor the best choice from a practical viewpoint
Disagree.
The "Proven" criteria is a bit of a through away line that's meant to make non technical decision makers feel more comfortable, for the simple reason there is no "proven" i.e. off the shelf design that meets all of the operationally relevant criteria.
Australia has a small blue water navy, there are three AEGIS frigates masquerading as destroyers and eight patrol frigates that have been upgraded to the limits of their stability to become GP frigates. Quite simply the RAN is too small to be able to operate sufficient single role ships to meet operational requirements, this means, no matter their specialty, every major combatant has to be multi role and with Chinas growing capabilities, has to have a high end air defence system.
The experience with the Hobart Class (Navantia F-104 baseline plus) was that it was too tight and too limited in terms of future growth. Additionally, although the primary reason the existing design was selected over the G&C International frigate, was risk reduction buying a "proven" inservice design (as well as anticipated but not achieved cost factors), the build was pretty much always in advance of baselined design data, i.e. Navantia was changing the "existing" design as the ships were being built, usually to fix issues that had been found on the earlier ships, rectified, but not baselined.
Lessons learned, ensure the designer has skin in the game, ensure the design is sorted and properly baselined before steel is cut, ensure you have a robust and enforceable contract and engineering change process, and above all, select a suitable design rather than one that seems to work ok for someone else.