Deterring these high-level creatures from approaching is also an interesting possibility. Also, keep in mind that at a longer distance (more than 6 cells), crossbowmen will deal half damage.
There won't be 7 cells. I don't know how you counted them.
Another good thing is that a direct shot will coincide with an accurate shot, at least on regular arenas.

I count the cells relative to the field. A crossbowman occupies the position of the closest row from the troop formation, by default. This means that one cell of distance is already subtracted from the battlefield, plus a firing radius of 6 cells, totaling 7 cells.



Isn't it a bit much to shoot across ~60% of the field and completely ignore armor? And where have you seen creatures whose deterrence method is a one-shot kill?
---------------------------------------------------
There is another option, you can base it on the second option, but instead of a piercing shot, give the archers an enhanced arrow: -50% armor on a permanent basis and knockback – that's a significant argument. Just the damage of 7-10 will have to be slightly reduced, otherwise, there will be an imbalance again.

The problem with this option has already been described by me. After enemy archers shoot at the crossbowmen, we don't have time to retreat them (only if they finish off enemies) and we end up with losses. These aren't Necropolises, which resurrect after battle. And what if the player has ranged units everywhere? Are we going to lose a hundred crossbows now because of this feature?

Well, the retaliatory shot can be replaced with maneuvering, then there won't be an obvious advantage, and even better, with slowing arrows (there will be a chance to delay the target's turn), because crossbowmen have low initiative, this won't cause an imbalance.