The Advanced Search by year-written returns spurious results. I searched for the year 1923, but most of the results were NOT written in 1923. For example, in the first page of results, the year-written ranged from 1523 to 1858.
Seems to me I had a similar problem some time back, and it had to do with hymnals frequently applying their publication date to all their instances. So for each of those hymns, presumably, at least one instance was in a hymnal published in 1923. Highly annoying, but at least it explains the annoyance.
It would be nice if there could be a search field for (actual, verified) copyright date, not date written or published.
It looks like the system is seeing the date written and a date altered as a range. I have put in a request to get this fixed as well as a request to be able to search the copyright field.