To see through a wall, or while inside a wall the ghost would need a special sense. Which is going to be hard to organise.
I think the Line of Effect rules will stop it from creating an effect such as casting a spell or using an ability with an effect outside the walls.
When creating an effect, you usually need an unblocked path to the target of a spell, the origin point of an effect’s area, or the place where you create something with a spell or other ability. This is called a line of effect. You have line of effect unless a creature is entirely behind a solid physical barrier. Visibility doesn’t matter for line of effect, nor do portcullises and other barriers that aren’t totally solid. If you’re unsure whether a barrier is solid enough, usually a 1-foot-square gap is enough to maintain a line of effect, though the GM makes the final call.
Though an emanation starts at the caster so line of effect to the origin is not really a problem then. However it also needs Line of Effect from the center of the area to each victim. Which it doesn't have.