Although the item itself is a ranged weapon, it fires a projectile that does not deal ranged damage. I'm pretty sure the reason this happened is that it shares the same projectile as falling stars. I am not certain if it was intentional because the super star cannon fires projectiles that deal ranged damage.
No melee/ranged/magic damage type means no crits. There is no such thing a neutral crit chance. Items do not correctly copy their crit rate to projectiles, but they do copy damage. For this reason, ranged damage boosts work but crit does not. Also Frost Armor won't appy Frostburn.
This is fixable even without creating a new projectile type or fixing the critical hit bug, because individual projectiles can be set to be melee, ranged, and/or magic. Stars spawned by the star cannon could have the ranged flag set to enable critical hits and Frost Armor's Frostburn. The fact that the bug can be fixed probably won't matter because fixing the bug would result in a significant buff so it can't be fixed without being approved as a balance change.
