Don't sweat the acetone penetrating the primer pocket thing. Maybe you *could* detect acetone inside the case using a sensitive gas chemical sensing thingy, but the normal acetone residues within the powder itself would probably contribute far more parts per million.
Humidity generally won't kill ammo. Immersion in water for many days/years can.
Laquer away, friends! 100 years of military experience shows it does NOT harm the primer or powder.