I wonder if there’s a smart way to sync or record what you do and repeat it in other layers by scripting? Moved a point → move it in other layers. Copied a path between two glyphs → copy its counterpart in other layers too. Perhaps even ran a script → run it in other layers?
I tried copying/moving stuff by saving a copy of the layer, comparing changes to it, and then applying the changes to other layers, but it messes up the undo manager. Any better way?