If I create a macro that uses the "Click at Found Image" action using an image copied from a retina screen, should that action work on a non-retina screen too? Or would I need to have if/thens that searched for a retina found image then clicked on retina found image, and also a non-retina found image search and click on non-retina image? My main computer has a retina screen, but I have a shared sync file that I use on a 2012 Macbook air.
It depends on the image and on the "fuzz" setting in the Action.
You will just need to experiment on the two screens to find out.