But the Map Troops feature doesn't show the troops they have with them either (unless I'm missing an even cooler feature), just the fact that there is at least one noble of a particular army in that region.
Sure it does. Look at the borders around the army icons.
...I haven't made a key for them yet, but roughly:
100 < CS <= 1000, green border
1000 < CS <= 7500, yellow border
above that, red border
Within each border color, there are 3 widths, that give an indication of how much CS within that range is in the region.
