I agree that the situation is assymetric and that the reason for it is alpha striking by the player.
Put simply, alpha striking is very easy, always available and is the most reliable way of dealing with any tactical situation, especially Chirons. The only thing that is even easier is casting electric reinforcement twice and then recover each turn (which makes the whole squad all but invulnerable and can be done every turn).
But as soon as you step out of an alpha striking scenario, it can make sense for the player to use acid weapons. The acid cannon is guaranteed to eat through any armor in one turn, and deal massive damage on the next.
All this to say that yes, acid needed buffing, and now its need nerfing (which is already on the way:
)
For explosive Chirons the biggest problem IMO is the (occasional and unpredictable) double damage from explosion bug. Without it, it would be quite hard for an explosive Chiron to one-shot kill/massively cripple one or more squaddies.