“Changing the days of the week, the planets, etc., would have been quite a feat even for the resourceful Puritans.”
Wrong. In their own country - right here in North America - they could have easily done it. Also, Puritans used “pagan” marriage practices: wedding rings, exchange of vows in public, etc. Even their clothing could be called “pagan” according to your standard.
“The modern idea of religious pluralism was quite foreign to the 17th-century way of thinking. The Puritans never pretended otherwise.”
Hence, their inconsistency and hypocrisy.