So this new ticket escalation service is quite the hero, even if QF shouldn't need it.
Within a day, and on a Saturday no less, I received a ticket (not a reservation or travel document or whatever) confirming our original date and time. Happy with that outcome however we now have to make our own way between DXB and AUH. Not the end of the world but we did like the idea of the surface segment being included, one less thing to pay for and worry about.
It remains a mystery as to why it offered the destination and then couldn't be ticketed. It could be removed from/changed in the system as quickly as it takes to say "Taiwan is not separate country".
Anyway, great recovery but still need to fix the reasons for getting into the mess in the first place. Also glad we don't have to worry about EU261, if applicable. I'm sure
@kangarooflyer88 could set up a decent side hustle acting for affected pax