OK, here's a weird "bug"
The tool priced up the following business class 5-continent itinerary for me:
It priced it as a 3-continernt itinerary! Base fare of JPY656,300 instead of JPY895,200
I changed the date of one flight (SYD-NAN), turning the first SYD transit into a stopover, and the base fare jumped to the correct DONE5 base fare.
When you go to pay, a pop-up gives you the choice of ticketing with JL (which requires you to phone to pay) or with QF (which you would pay online, and "Qantas will issue your ticket automatically".
Sadly, the itinerary is not quite what I want (i want to transit DOH to CPT, but the tool fails if I enter that), and also I don't think I'm brave enough to risk ticketing the "error fare".