The Marathas made exstensive use of guerrilla warfare, the hills and platues which cover a lot of that area were ideal for this.
The way CA has been portraying this uptil now, is not at all satisfactory. What they should do is, that a general who is good at guerilla warfare, should be able to, sort of ambush the enemy, a lot more easily than usual, and the troops should get a bonus during this, and should be able to retreat quicker than regular troops.
Having troops being able to hide anywhere doesn't count, because for one, guerilla warfare never took place on flat terrain, and secondly, these people used to hit and run fast.
Hidden troops can hit, do damage, but take a lot more damage than it is proper, and more often then not I've simply lost my unit.
Hopefully as this is a new engine and all, they'll have something better this time around. Specially with the great range of area and terrain available, the effect should be more 'visible' than before.