About to start an ex-CAI, my first RTW - thank you Central Bank of Egypt! :)
I booked a boilerplate DONE4 itin that worked on the OW tool, and plated that with the BA GGL team on 125 stock to lock in the low price.
Whilst the crazy low pricing was still available, I asked BA to quote a new, better optimised itinerary, but their rates desk said the itinerary didn't meet the requirements. I did two rounds of this before putting it on the backburner; now picking this up again as I will soon fly the first segment and I will be able to change using historical fares.

Routing 1 CAI-LHR-SIN-NRT-BLR-SYDxTBU-SYD-JFK-MEX-JFKxLAX-DOHxBCN-DOHxSEZ-DOH (changing the DONE4 into DONE5, by adding Africa)
BA's rates desk responded:
Routing 2 CAI-LHR-SIN-NRT-BLR-SYDxTBU-SYD-JFK-MEX-JFKxLAX-DOHxBCN-DOH (keeping at DONE4)
In this case BA told me that the itin was not valid according to the OW tool, and left it at that.

Is the BA rates desk correct, or are they missing the plot?

For my ex-CAI RTW ticket, I have one of the following segments:
Originally, it's YYZ-HKG arrives at 5:00am and then connecting HKG-BKK departures at 8;00am, all by CX
Now, I want to change the HKG-BKK flight to a later one on the same day, say departure at 13:00pm.

My question is :
1. Will this change be deemed as a "ticketed point" change or not? If not, then I would assume there should be no $125 change fee.
2. Would it be easier to call QF to make the change after my first segment is flown, rather than calling them now?

As long as it's under 24 hours then it shouldn't be any issue whatsoever. It's the same airline, same connection point, and still a connection (under 24 hours).

2) Yes, very likely easier to do after your first segment, but how much time do you have? It might take 2-3 days to get done depending on the agent you get.

I may not be directly offering suggestion or advice, but just a data point.
I had a very similar situation. My DONEx first flight (on CX) arrived at HKG. By plan, I had a very long layover (can't recall exactly, but it was several hours) before my next CX flight. While inside Wing First Lounge, I handed a spreadsheet with all flight details of changes that I wanted to get done (make sure all flight had D availability). The agent called another agent in the HK office. She then told me to just relax.
Long story short, it was all done according to my spreadsheet. We were in the lounge for a long time. During which an agent kept it informed of the status (being worked on). When the first agent went off duty, she introduced me to the next agent who was to "take care" of me!
I think your 3 hour layover maybe tight (even if YYZ-HKG is on time) if you want to get it done at HKG by CX. I might say, I was happy with CX's performance as being professional.

I'm pretty sure chivalryflyer is on a QF ticket so CX wouldn't have any ability to do changes like that while you're in the CX lounge. Sounds like you were on a CX ticket, in which case they could be very useful.

Awesome! I used to fly through HKG regularly when I was doing AONEx tix. Which person helped you with this, was it the person at the door checking admissibility?

Is your ticket a QF issued one? In fact, I have called CX HongKong asking if they can make changes to the segments that CX flies, and CX agent told me a clear NO. She said I have to ask QF to do that.
Exactly, mine is QF ticketed.

Thanks！ Yeah, mine is Business RTW ticket and the HKG flight is one and half month after my first segment, so I believe the time is enough to do it after my first segment.

Yes, I was on CX ticket #160.
In checking my original record, I had 11 hours layover time! I simply wanted to ensure I had enough buffer, just in case.

No, not the person who welcome me in. I talked with one of two staff member at the desk. When they understood my issues, they led me into small office where 2 lady agents were working. One of them took over, and she called an office in Hong Kong. I was not aware of the particular office by name as such.
My guess is they would refer more complex ticket re-issue to HQ office in Hong Kong.

As answered above, my ticket was issued by CX.

Ex-CAI route change info only. As prev posted I was originally on a QF issued ticket and able to get AA to take it over - thank goodness!. Anywhoo for anyone interested who is on an AA issued ex-CAI ticket I was forced to make changes to my routing yesterday as I called to push out my SEA-DFW-SCL sector and discovered that AA are discontinuing the route from end of March. This forced a change to SEA-MIA-SCL. I have not yet flown the first sector so the agent suggested a $125 change fee was likely and "possibly" a reprice if the fare had changed. This was obv concerning but since AA do not have a published XONEX fare out of CAI any longer I was prepared to wait and see - well good news is they came back today with the fee and it was just the $125 change fee. So it would appear that for at least some route changes a reprice wont happen on ex-CAI XONEX's of course YMMV. I'm not sure about taxes as don't know if a change between DFW and MIA would have seen any additional taxes/carrier charges under any circumstances (I assume adding a stop like LHR or CDG must incur an additional tax fee on top of the $125 at minimum)

If AA discontinued a route, thereby forcing such an involuntary change then there should have been no $125 fee assessed.