I understand it is impossible to make these things fit in a proper relational model. For instance, modeling dates when artworks are made circa a date, between 2

I understand it is impossible to make these things fit in a proper relational model. For instance, modeling dates when artworks are made circa a date, between 2 dates, started by someone and finished by someone else, is very complex. That said, they should at least try. Being able to sort artworks by date seems pretty fundamental to me! Look at the data released by the Cooper-Hewitt that someone posted below. They actually have some kind of structure!