I’m finding if I use the Subtract front path shortcut at the bottom of the Transformations panel, the corner components I’ve used elsewhere on the same glyph get decomposed.
EDIT: in fact other overlaps are removed, and smooth (green) nodes turn blue, too.
I’m not sure I follow what you’re saying, but at any rate I want to clarify that the overlaps and corners that get lost are not in the region I’m subtracting, but way over on the other side of the letter.