Quemapueblos, Wargaming NA Producer:
Devs sent me an update this morning to add to the patch notes:
Bonus from the Concealment Expert skill is now applied to the basic visibility of the ship similar to the camouflage modifiers and the Masking System mod.1 modernization. Previously, this bonus affected the fines to visibility, such as fire, main battery, AA defense and anti-torpedo armament.