Multiple flights.
This isn't rocket science here. You can easily fly from California to New York, then from New York to Europe. From Europe to China. From China to Japan.
Or, the southern suggested route: Chile to South Africa. South Africa to Australia.
On a flat Earth model, the distance, one way, or the opposite way, should be much greater in the southern trip than the northern.
And I've flown both ways on the northern path. From Illinois to NY, then to Germany. On the trip back, we were able to find a cheaper flight that was a connector through China.
Now, quite obviously, on the FE model, the southern trip should take roughly three times as long (I haven't done the math, so this is an estimate) as the northern trip would. If it doesn't, we have a glaring issue.
It doesn't. You have a glaring issue.