A while ago I mentioned using JOSM’s validator to check relations. That works, but finding the relations to check can be a problem.
However this answer to an Overpass question allows these to be found, by changing the Overpass search. For example changing the search part can find other things:
relation["boundary"="civil_parish"]({{bbox}});
which is https://overpass-turbo.eu/s/22F9, currently finds one broken relation (and highlights the nodes on either side of the break).
Other useful checks include:
relation["place"="county"]({{bbox}});
relation["boundary"="historic"]({{bbox}});
relation["boundary"="historic_parish"]({{bbox}});
relation["boundary"="historic_diocese"]({{bbox}});
relation["boundary"="historic_church_province"]({{bbox}});
relation["boundary"="national_park"]({{bbox}});
relation["locality"="townland"]({{bbox}});