8th edition Empire FAQ says-
Page 39 – Countercharge
Change to “In the enemy’s Movement phase a detachment that
is in close support, and that has not been charged itself, may
countercharge an enemy unit charging its parent unit. The
countercharge is made at the end of the Charge sub-phase,
after all normal charges have been carried out.
I had a parent unit of swordsmen and a detachment of free company in close support on its flank. Opponent charges my swordsmen with big skeleton unit, and charges my free company with grave guard. I react for both by holding. Both charges should have gone off without a hitch, as rolls of 5 or less were needed. But the grave guard charge roll was only 4 inches, so while the skeleton warriors hit my swordsmen while the grave guard petered forward 3 inches and stopped.
Because of this I then counter-charged with my free company detachment into the flank of the skeletons, there was just barely enough room, and we proceeded on with the game. However, now that I think about it, maybe that shouldn't be allowed? The words is, "has not been charged itself".
Does "has not been charged itself" mean
a) Has not been successfully charged?
b) Has not had a charge declaration made against it?
How do people play this? In 7th edition, this never came up because my opponents always were within charge distance when doing something like this, but in 8th there is always the chance that you roll ridiculously low and a charge that should succeed fails.