Agree as well and that was what I thought all along, until I see the mismatch on the eTicket. Out of curiosity, I called the hotline to clarify and got the same answer of "if stopover is more than 24 hours, allowance is based on regional flight rule". I suspect the system that spits out eTicket actually works like that as Kaka said it shows leg by leg if stop was more than 24 hours.

But I checked the rule on the web site again and no mention of the 24-hour limit as long as the trip touches America. I guess as Kaka said, better have the rules handy if under this situation.