Today I found a record where the marriage date hadn't made it through ged import (this was in 2013) it had a note in the auto generated bio of Could not interpret date in Marriage Date (21/09/1834). To say wiki couldn't work out the date, 29/09/1834 so wiki had been trying to make the 29th September into the 9th of the 29th month and failed back then. Because of this error I checked the birth date and wiki had mis-interpreated it back then so something like the 2/4 which should have been 2nd of April had become the 4th of February.
As this error message was in the biography not the fields, so I'm not sure the db_errors project would be able to find these faults, but certainly something for people working on English records to watch out for. And maybe someone will have an genius idea of how to find them all.
Though maybe looking at how many records have a full birth or death date below the 12th day in a month ?(cause if it was over 12 days it would have rejected it as thinking English way of writing days were months) and ,ENGLAND in the place and have a spouse but no marriage date and place might find them but it would likely also find thousands of others I think.
I will try to find an example that hasn't been corrected, but seems to be quite a few of these on the Blakey records from Newcastle England.