How sure are we about the wiki entry implying you won't pay for a base fair increase if reticketing after departure?

That's what I understood too but two of best AA rtw helpdesk staff have both suggested it's likely my ex CAI ticket priced at Cathay's rate last week would reprice if I rerouted even if I did so after departure.

The rules are clear that you will pay for a base fair hike if you reticket before 1st departure or if you add to the number of continents, but is does not explicitly say you won't if you reticket after departure without a change in continents. That strongly implies you shouldn't pay for the hike if reticketing after departure but note how b below does not say you have to pay for the difference in taxes etc. which we know you do so I can see how Cathay (/AA rtw desk) might argue the base fair hike is treated the same way.

Prior to departure: "If the fare level has increased since ticket issuance, the difference between the old and new fare will also be charged."

After departure (wording in full for Eff 1 September 2018 rules):
a. Changes are permitted provided ticketed points remain the same.

b. Changes to ticketed points are permitted at a charge of USD 125 per transaction.

c. No Show requires rebooking at a charge of USD 125.

d. If the rerouting results in an increase to the number of continents previously charged, the ticket shall be recalculated. Ticket may be reissued to any applicable Explorer fare validating all rules of the new fare except for restrictions on retroactive use. Rerouting fee applies when the resulting fare is less than or equal to the original fare. No refund applies. See Upgrading provisions when recalculation results in a new fare basis at a higher value