Firstly, a big apology. I have posted my recent query in the wrong thread. They should have been in the FAQ thread. That's a big mistake on part. It's a bug-bear of mine when threads go off-topic and now I've done it. I've alerted the moderators and asked that my post and everyone's advice be moved to the FAQ thread. Until that happens . . .

Secondly, I've managed to speak to the AA RTW desk.

In addition to the USD125 re-route fee I'd be up for and additional USD674.94 in taxes for KWI which seems huge.

Two important points. First, my ticket involved an involuntary re-route that resulted in CX becoming involved with my AA ticket. As a result, AA can't see that I've actually paid the UK APD or whatever the appropriate taxes are for a stopover in LHR, rather than a transit. Therefore, the above amounts included "about $300" for these UK taxes that I have actually paid. But even at about USD370 the taxes for KWI seem ridiculous. But, second, as Calchas suggested, AA said the taxes are re-assessed on all remaining unflown sectors, not just the one final sector I'm flying. Therefore, maybe the USD370-odd is not just KWI taxes but increased taxes on the five remaining sectors I have.

I was on the phone to AA for well over an hour and that's with my call initially being answered very quickly. The rates desk clearly has a complicated job. The RTW agent I spoke with was kind of reluctant to get me "quotes" on the taxes and I can see why. That said, it would be stupid of AA or any airline to expect a passenger with flexible plans to just say 'Go with x city, whatever the taxes are, and I'll pay them'. I have a choice of a few cities so I'm going to favour one with low taxes.

Finally, while waiting for the RTW desk to contact the rates desk I looked up KWI on Wikivoyage. In big letters: "Entry will be refused to citizens of Israel and to those who show stamps and/or visas from Israel". However, I called the Kuwait Embassy in Canberra this morning and the lady I spoke with says it's no issue for an Australian passport holder. I would feel better if that was written somewhere so I'll have a look in the trip report thread.