A big AOE hit should not be done with traces alone, they should be used in combination with overlap. Else you’re tracing for every single actor in the scene- which is a terrible idea. Even then, traces are not super expensive.
Async nodes work by using a process disconnected from the main game thread- as such, it can’t interact with it. Traces need to be done in the main game thread in order to properly query the level.
Async nodes are only to be used when a result can be procured in isolation- basically pure nodes. Think calculating PI to a quadrillion places- you don’t want to wait for that to complete on the main thread before you can continue playing the game. Though if you absolutely need Pi to a quadrillion places at that exact moment, then you will have to wait for it.