Hi Rene. Sorry, seeing this message only now. The residential polygons have also been converted into relations. Eg: https://www.openstreetmap.org/relation/19349201

While relations editing is more complex than way editing, it is the preferred method of mapping complex overlapping boundaries especially if the length of overlap is lengthy and if there are 3 places sharing the same way. In this instance, Bangsar Park, Federal Hill and Urban Community Forest all share the boundary way - hence they have all been converted to relations.

You will notice that in my relations tag, I have included previously=way:1136336131;way:705649073

So although the relation element is new with no previous history, one can see that the tag values were derived from the previous way polygons and can visit those still existing polygons to check its earlier history before the relation was created.