Here's the responses from QFF. Spoiler alert, there's no access.
Thank you for your email and for taking the time to follow up. We appreciate you letting us know about the response you received earlier, and we’re sorry that it did not address the feedback you provided.
Regarding your question about access to the Qantas First Lounge in Auckland, although your flight was booked through Qantas and carried a Qantas flight number, lounge access is also determined by the operating airline. As this service was operated by Air Tahiti Nui, which is not a Oneworld member, Qantas lounge access is not eligible for this flight.
We understand this may have been disappointing, especially as a Platinum Frequent Flyer, and we appreciate you reaching out for clarification.
I responded with
As you've said it is disappointing, and is contrary to my interpretation of the lounge guidelines.
It looks like this is the end of this but it is poor form by Qantas.
What makes no sense when considering lounge access is that I received both status credits and points for the fight.
And their reply
While lounge access is not eligible for this particular flight, you were still able to earn both Qantas Points and Status Credits because the flight carried a QF flight number. Earning eligibility is determined by the marketing carrier, whereas lounge access is determined by both the marketing and operating carrier. In this case, the flight was marketed by Qantas, which allowed you to earn points and Status Credits; however, it was operated by a non‑Oneworld partner, which meant lounge access was not available.
We acknowledge that this distinction can be confusing. These benefits follow different eligibility rules, which can sometimes lead to outcomes that appear inconsistent.
We hope that this helps clarify things and confirms the information for your convenience.