So... They carried numerous 20 ton slabs of rock across two oceans and an entire continent, then when they finally got to England they built Stonehenge and then just turned around and went home again?
Makes perfect sense. I have no follow up questions.
Somebody is confused. There is a Stonehenge Aotearoa, which is a replica built in New Zealand. The ancient Stonehenge was almost certainly built by ancient Celts and the stones were taken from a few hundred miles away in Wales, which itself is an impressive feat.
I think the "not from England" part is probably because of the recent news that the alter stone is from Scotland. like you say, a lot of them are from Wales, it's just the alter stone in the center that's from far away. Not Maori though.