I’ve been using gaps in the UPRN import to find badly aligned houses. First I downloaded houses without UPRNs into JOSM:
I then went through finding the houses that were badly aligned (rather than stretching over two parcels, not being parcels or having more than one UPRN because they were divided into flats) and moved them. With terraced houses I downloaded the whole terrace and moved that.
So far I have done adjustments in Barnes.