I'm not in front of Logic at the moment, but I think you are talking about the tilde key. It looks like this: ~
And it is right underneath the escape key. Using the tilde key alone is the default key command for toggling the catch clock position key command. Not sure what it is with shift added (not in front of Logic currently).
The behavior of Scroll to Selection, when selected from the View menu will place the selected region within the viewable area of the Arrange window.
So for example if you select a region from a large Arrange window (screenset 1), then go to screen set 2 which has a narrow Arrange window but large Piano Roll editor, then click the Scroll to Selection command from the Arrange>View menu, the selected region (where ever it is in the Arrange), is put into view, whatever the size of the Arrange window in a given screen set.
Having a working key command would be helpful to put the region in view in my example screen set 2.
Shift-return will then place the playhead at the beginning of the selected region.
I only know this as a result of trial and error last night while redesigning my template screen sets.