I made a distinction between the lines on a map, and the actual occupied territories, with cities, forts and trade routes. A border on a map is not the same thing as a territory that is occupied and well-defended. As mentioned in the book, prior to the Seanchan occupation, Altara's ruler barely could consolidate power in Ebou Dar. Furthermore, Salidar, which is close to Ghealdan, was an abandoned town when the Rebel Aes Sedai came their for a refuge, and we are specifically told that many of the Northern villages along Altara's border were abandoned after the Whitecloak War. This is why I'm saying it is more important for Andor to defend the road east, and if Murandy ever gets it's act together, it would be better if they did the same. A road north to the Two Rivers would do little more than act as a possible sanctuary or fallback position and while the Two Rivers could act as a temporary reinforcement, they simply don't have the necessary numbers if the Seanchan had pushed that far into Ghealdan, it would be hard for forces from the Two Rivers to push them out.

In the grand scheme of things, in order to provide military support, Andor would need both roads because if Ghealdan is threatened, and they can only mobilize across one road to reach them, considering the size of Ghealdan relative to Seanchan territory, the battle would already be lost.

The best solution for Ghealdan would be for Andor and Ghealdan to take the territory north of the Jehannah Road, and consolidate the area by making multiple roads through the Wall east. Technically, the Two Rivers itself could easily find itself in the same situation as Ghealdan, and if the Seanchan pushed their borders north, the situation for Andor and Ghealdan would worsen. This is why I'm disagreeing that a road north would solve anything, while fortifying the eastern territories would be a better solution.