"Buyer beware" so the saying goes.

It is well known that Garuda are not part of Star Alliance. Air NZ, like many other airlines, offer interline fares which involve carriers which may not necessarily be part of their own frequent flyer scheme. For example, AKL-NZ-HKG-CX-LHR is a common route to London offered on the Air NZ website. However, you do not earn any points for HKG-LHR as the flight is operated by CX.

As for the second issue to New Caledonia, Air New Zealand has an air share agreement with Air Calin (where Air NZ buy a block of seats and market them under the NZ flight number). Air NZ are very clear on their website that in order to earn Airpoints and have lounge access etc, you must be booked under the Air NZ flight number. Also, no Status Points can be earned even if the flight is booked on the Air NZ flight number. The reason why the flight didn't show on the Air NZ website is most likely that they had already sold the block of seats that they had be allocated.

https://www.airnewzealand.co.nz/co-o...tners-aircalin

A complete non-issue here I'm afraid...