Thanks for the reply and the detailed explanaition! That sounds like a quite complex situation and I am not absolutly sure how I would map this.
Someone already changed the nodes to traffic_calming=island:
https://www.openstreetmap.org/node/11976014275
https://www.openstreetmap.org/node/11976014276
That does not look richt as there are now 2 nodes for one traffic island. And this is against the good practice "One feature, one OSM element":
https://wiki.openstreetmap.org/wiki/One_feature,_one_OSM_element

I am not sure how to fix this. I opened a note to make this topic more public:
https://www.openstreetmap.org/note/4474129