That's a great question.
Short answer: The Gods of Etheria are not omniscient, all-knowing, all-seeing beings that have always existed. In fact, most Sortilegian scholars call them "The New Gods" because they wrested power and followers away from the Elemental Lords who predated them.
Can the Gods see a mortal of Etheria at will? The Gods would certainly like for their adherents to believe that. Is Taranis instantly aware when a Warlock commits a dark act? Probably not. But if he wanted to focus in on that Warlock's life, he could do so, and if so, it would appear as if he was instantly aware of a specific action.