Okay I've hopefully replaced most of my slop now with well-aligned buildings by JOSM buildings + uberterrace plugins. If you spot anything else please let me know. Thanks again.

Indeed, I'm rather new to urban mapping. I am just starting to learn JOSM and see that with the building and uberterracer plugins one can build beautiful, perfectly symmetrical terraces. I will find and delete whatever ugliness I have introduced and just use JOSM going forward. Thanks for bearing with me.

I am beginning to learn the JOSM editor as it looks like all serious mappers end up there. Got to build the skillz to get better at this.

Gotcha. Is there an efficient way of "snapping" two ways/buildings together? I'm using the iD editor and manually moving traces to ensure they are adjacent but not overlapping is a bit laborious.

Thanks for pointing these out. I have manually recreated many of the ways to better reflect terraced buildings.