As some people argued at length in other topics, this is factually anachronistic. Even the fact that you always know they're coming through is, tbh, anachronistic.
sorry but what is here anachronistic, that enemy armies move through my territory or that we can see armies "about" 3 baronies away?
You could not move 10.000 men at arms through enemy territory without someone noticing, even in the sparse populated middle ages, that is not anachronistic.
To see enemy from afar as if we already had drones and satelite imaging, yes that is, but it can be fixed and explained. Frist, we should not see any army outside our borders/realms. Second, as statted above, you cant move a few thousand men at arms without someone noticing, therefore you would see them in your territory. Third, armies use mounted scouts, so if you have an army somewhere, it have a small visibility range around it. It is not perfect but what is? I can send a marriage proposal from bohemia to novgorod (2000miles) and have an answer in one day.
And CK would actauly profit if it had some sort of fog of war, I like it, that battles are just a numbers game (if we had full control, ie Total War games, there would be no way for the AI to stop the player) and carefuly moving around and laying ambsushes etc would add a layer of strategy.