Collateral Damage does nothing to change the fact that artillery and radar artillery are extremely powerful now that they target units before anything else.
In my ideal world, the fix would involve giving a hard-to-kill city improvement a bombard defense, which needs to be destroyed before any units can be damaged. Walls already do this in the ancient age, but you currently can't add bombard defense to anything else because it would not work for cities above size-6. If they fix this, the civil defense city improvement would be a great candidate for bombard defense of, say, 48 (so it has a 20% chance of getting destroyed by artillery).
In my ideal world, the fix would involve giving a hard-to-kill city improvement a bombard defense, which needs to be destroyed before any units can be damaged. Walls already do this in the ancient age, but you currently can't add bombard defense to anything else because it would not work for cities above size-6. If they fix this, the civil defense city improvement would be a great candidate for bombard defense of, say, 48 (so it has a 20% chance of getting destroyed by artillery).