How good (or bad!) are those “cheap” range finders? How big does the “target” need to be? What is the range? 100m? 1km? I’d love to see a post with a bit more detail about those!

Nice work, and a very good write-up!

Looks like there are some remaining issues with invalid polygons, however. For example, relation/9727078, way/699994013, uses the same node twice (6537466518). relation/9712099, way/698995586 touches itself, but without using a repeated node. Both are flagged as warnings by the JOSM validator, but I believe self-touching polygons are considered invalid.

(I am Swedish, writing in English just for consistency with the diary entry :-) )