TFung - Okay I verified with the AA RTW desk and this is what they say -

You are allowed only 1 Transcon. A Transcon is what borders the Pacific Ocean and the Atlantic Ocean. So your YVR-JFK is permitted.
And then subsequently your additional sectors will be permitted within the US.

Backtracking between PPT and South America is definitely not permitted.

But there will be new rules effective May 8th - this is in additional to the 5% across the board fare increase:

The 3 stops per continent will be discontinued. Instead, within each continent, other than North America, you will only be permitted 4 segments. If you squeeze in 5 stops per continent, then you can! However, additional stopovers can no longer be purchased. Instead, you are encouraged to purchase OW's Visit Europe, Visit SWP, Visit Asia, Visit North America fares. Please note however that these will be available only in economy class.

Continent of Origin will be permitted 2 stops and this can be anywhere and not only at Intercontinental Gateways.

TFung, if you issue the ticket in BKK, you might still get a discount from the local travel agents there, but unlikely if you issue the ticket in North America.