I was chasing down a rendering problem wondering why the name did not appear at https://map.atownsend.org.uk/maps/map/map.html#22/53.95317/-1.08447 , and then realised that someone had removed it!
To answer the question, the easiest way to "undo an erroneous change" in a case like this is just to "edit it again and add the name back".  There are various changeset revert options, but none are as quick in a case like this as just editing it, as I've just done in https://www.openstreetmap.org/changeset/155773016 .  
Cheers,
Andy
