I got a price back late yesterday, almost $5,000 more than it was meant to be. I called the RTW desk back to discuss it. I explained what the issue was and that it didn’t appear that they had applied the ‘Canadian exception” as stated in the fare rules. The agent said that they didn’t have the rules and that it was all the rate desk (though she later quoted from the fare rules...). She called through to the rates desk while I waited and came back saying that they ‘stand by the price’ and that it was correct. At that point I ended the call as I had to go to work.
Just after I got to work, I realized something they said which may be the cause. On the phone, the agent said “first”. So I got curious and looked up the prices...

AA RTW desk quote: 12,923.04 CAD
Online tool quote: 9,144,800 KRW (~8,319.29 CAD)
Taxes
AA RTW desk: “about $900” (from phone call to RTW desk)
Online: 615,500 KRW (~559.93 CAD)

DONE3
Korea: 8,529,300 KRW (7,667 CAD)
Canada: 10,199 CAD

AONE3
Korea: 13,322,100 KRW (11,975 CAD)
Canada: 13,799 CAD

I’m thinking they may have applied the exception, but priced it as an AONE3 instead of a DONE3. The Korean base fare for an AONE3 appears to match up to the quoted price once the claimed taxes are added and is closer to the KRW price they said on the phone.

Just put in the same flights/dates into the online tool as an AONE3. Got 13,937,600 KRW (~12,675.51 CAD with the taxes being the same as the DONE3 amount).