If you use the rolling mode with these weapons, you either one-shot the enemies or bounce off of them, so piercing does not affect this attack style.
However, piercing does affect the flick attack mode for both of the weapons. The projectile ink that is flung from the weapon will pierce through enemies. This is particularly effective with the vertical flick from the roller which is very powerful and can clear long lines of jelletons with a few piercing chips.
That being said, based on the preferred chip colors, it will almost always be more synergistic with those kits to increase the rolling damage/speed instead, which would render pierce largely useless.