I'm not using your navigation generator, since I haven't figured it out.
I first noticed the limitation of CanPathTo function when testing the script that finds spawn points for the Rift Orbs. I would generate hundreds of units, randomly over the map, and test if they could path to a player.
First test showed all units spawning randomly around the entire map.
On the second test, any units that failed the CanPathTo check would be destroyed. This would only leave the units that could path.
On the second test, I noticed the units that remained were usually no further than 5km from the player spawns, instead of randomly over the entire map. The CanPathTo script appeared to abort early, causing units too far away from passing the test.
This wasn't an issue for the Rift Orbs script, as I had intended to limit the max distance Orbs would spawn from players. But this does become an issue when trying to test for pathable players on larger maps, which can cause the script to find none and then default waves to amphibious units on a map that is all land.
I plan to set the script as being able to be disabled by players, as there may be maps where players are on plateaus and they want all land units. The feature is more for new players who aren't aware they need to switch land waves to amphibious on water maps.