Well I didn't misunderstand, but I did miss the presence of the relation on those roads. I'm aware that the relation is the correct way to define an area such as these and that the tags are pretty much useless, however they were pre-existing on the existing sections of the boundary and more for the sake of continuity I retained them.

As for missing the relations, I'm just not used to the new web editor, I more used to the potlatch editor where relation information was front and centre. I guess that whole set of changes can be reverted then. However there is stick a break somewhere as you can see, the park isn't be rendered. I've fixed it a couple of times in the distant past and I've grown tired of finding it broken yet again.

I've no idea how that duplicated/offset section was created, I'm going to blame the editor. I was working on fixing a large missing section of the western park boundary between Hayfield and Chapel-en-le-Frith. Also an incorrectly tagged section at the southern boundary. At present the Park doesn't render at all in those renders which show them (osmand is one example) because of various broken parts - this wasn't always the case. I hadn't finished the fixes. The section you highlighted can (650691621) can be entirely deleted but to revert the whole commit would wipe out a lot of work on the correct path.

This is the section I was fixing - way/162867451#map=12/53.2709/-1.8864