Currently, of the Alchemers, the Cryotech series is the only series that actually negates itself, effectively halving its chance of inducing status on a given enemy. Compare this to its bomb equivalent, which not only has no such drawback, but due to its DoT nature it actually refreezes targets quite frequently after they have thawed or been hit.
My suggestion: Assign each volley (set of two bullets + ricochets) an ID. Then, if one freezes an enemy, store that ID in the enemy's instance and do not allow bullets of the same ID to unfreeze it.
Ice should take more damage to break. As of now shivermist easialy trumps all ice items due to the ability to re-freeze enemies after the ice is broken.