Sounds like an interesting idea you’re working on. We’d love to know the use case / project idea!
Here’s an example which I think should help - Face Follow Example 2d.ZPP (3.1 MB)
It has a large trigger region relative to Z.camera and pushed forward a bit in the Z axis (-5). It then has a ‘reaction plane’ tracking to the face origin with it’s trigger tag set to the same as the trigger region so it fires when intersecting. Using this intersection value, you can work out where the reaction is taking place and move a screen relative (2D) plane along the X and Y axis. I’d recommend having a quick once over the script to see how this is set up, but it should be pretty simple!
Hope this helps.