This tutorial may help you understand how collision properties work which will hopefully help you understand what I am about to recommend next.
What you should probably do is create a custom collision channel (by going to project settings tab then collisions…I think) and creating a custom channel for your destructible meshes. Set them to ignore themselves, block the pawn and block or overlap (I forget exactly I think both may work for your setup) “visibility” channel. This will allow line traces to register the mesh and you can fire off events from there.