I had many instances with airlines who refused to pay compensation when bags were delayed on the way to the home airport. And home airport being defined as the final airport on the ticket. Not just QF or LH. This is rather common.

However, in the OPs case QF lost the bags just sometime during the itinerary for a period of more than 24 hours. So in this case QF should cover some of the expenses incurred by the travel companion of the OP. No matter what the FF status or class of travel.

Weero, I would keep pushing and threaten them with the CTTT if other approaches fail.