Select a curtain wall and right click on your mouse.
You will notice there are some very handy selection tools for the Curtain panels and Mullions.
Now select a curtain panel and use the right click function.
I’m also sure you saw the “Select Grid” function. For the life of me, I cannot see how this selection works. No matter what Revit release I use, or what kind of Curtain System or wall I select, it is grayed out. All I can guess is it was intended to be a function, and programmer X from Autodesk forgot to put the coding in.
Anyway what works from above will be very helpful.