I think there is definitely enough story for a sequel, but I don't see why we couldn't have more.
One way to have a third is to put Jon's fake death at the end of the second, which we could call Liberation.
The war ends at the end of Liberation because of the work of the spies during Masquerade and even into Liberation. We will have lost our Iberan spies in the north, but perhaps the queen's secret spies can continue their work. The spy network could still be intact. Perhaps James Newberry will come in handy then.
Either way, my original idea for ending Masquerade could work for the end of Liberation. The third one could still be called Reunion because of the reuniting of Jon with the rest of the spies, including his wife and child.
Now, this is very far away, so the idea will change many times if we get this far and still like the idea of continuing.
But, perhaps Jon returns at the same time as another secret is revealed, putting the spies back in the game. Perhaps the spies find out that Jon is alive, so they go to rescue him. Hence, there are tons of things we could do with a third.
The idea behind the name Liberation is that Ibera finally is able to get out from under the subtle control of Handrin, not only ending the war but also putting Ibera on the map for the very first time. There is a lot of room for discussion here because we haven't talked about the history of the world much. (Someone needs to write History of the World Part 2!)
Plus, the name would be accurate in another way. Our characters would be liberating their kidnapped friend.