Flipping components <->, path direction, and overlap handling?

Scenario: One glyph design is based on another glyph, but mirrored/flipped with additional paths added.

One method is to use the first glyph as a component, flip it <->, and add the additional path(s). Then, let the Remove Overlap checkbox on export do its thing. This would be preferred, in case the first glyph design changes to keep the character of the two designs in sync.

Flipping the component <-> logically would have the paths in the component going the wrong direction. Or does decomposition upon export do the equivalent of the “Correct Path Direction” command?

It looks like that might be the case from a quick (not thorough) test. But, in 1.3.19b14a (483), the Preview section showed the overlap in inverse. If you reverse the added path (to put it in the “wrong” direction), the Preview looks good, but then the exported glyph has the inverse area. Perhaps that’s a bug? What’s the expected behavior when working with flipped components?

What is the recommended way to work on designs like this that want to keep the character of the two glyphs in sync?

I will have a look at it and see if I can implement it.

A revival of this issue because it is still alive also with Glyphs 2;
The question:
Is it safe to do transformations on Components which:

It produces even/odd overlaps as seen in the interpolation … despite that paths are showing total compatibility.