>"Blow to chest causes the zombie's heart to skip a beat."

Crit messages depend on the attack type, not the target (unless the target is non-corp or is missing an entire location). There's no way to remove or change that message for zombies without changing zombies to not have chests (its the rank 3 crush message for the chest), or changing that message for every critter.

The worst ones are the crit messages that include death e.g the rank 5 crush message for the head,

"Solid strike caves the [target]'s skull in,resulting in instant death!"

because that doesn't actually result in death for all critters, and there is a separate message that is tied to the critter when the critter does die.

"Solid strike caves the [target]'s skull in!" or "Solid strike caves the [target]'s skull in, that should be fatal!" would work better because it leaves the description of whether or not the critter dies to the critter death message. However there's no critter specific message for things like a 1 round stun from a chest hit, so there's no decent alternative to having inappropriate messaging for some of those crits.