Those kinds of attacks will probably require editing of the weapon effects themselves, or triggers.
You can test if basic scope selection works (Source Point and Target Point specifically), but ultimately there's nothing that uniquely identifies fancy AoE patterns or odd missile trajectories. Also some attacks, like Lurker spines, acid puddles, Psi Storm etc. don't really have a "direction" you can represent ingame.
Now, if you code each attack individually, you can make it read out the missile position/AoE epicenter fairly easily since it has access to the full scope of its effect chain, but that's a lot of work and you have to stay on top of it with all future additions.