hi northchun, you'll find that in Australia, common practice has been to map out roundabouts as a circular way and tag them as junction=roundabout. I realise this does conflict with https://wiki.openstreetmap.org/wiki/Tag:highway=mini%20roundabout?uselang=en but due to this longstanding practice you should consult the community before changing things around.

Regardless the style of mapping you've used here adding a single node not connected to the highway=* way is incorrect and would cause validation issues.