Adam discussed the events of Fume Cathedral with Silvana many times, and at first, Silvana didn't have all the answers.
However, when he became K2-Phantom, Silvana's rank also increased, giving her access to new information as well as previously classified terms.
The Irregular Energy was one of those. There was nothing wrong or dangerous about this information, but the government didn't want the K0 and K1 Phantoms to be scared before their future - the Wild Lands.
The Irregular Energy and the External Artifacts were part of the Wild Lands, not of the Pacific Lands.
The government was sure that for many Phantoms below K2-Level, it would be a severe blow to morale if they found out before time that they were only fighting in the starting zone.
There was another key difference between the Pacific Lands and the Wild Lands: the Wild Lands were simply much farther away from the Citadel.