For vast majority: yes, though I have not considered tagging them also as traffic_calming=island
I have seen some build (deliberately or due to incompetence, hard to say) that provide refugee for pedestrians and allow them to cross road in parts but result in no traffic calming whatsoever, cars can drive like they have not existed anyway.
There are also cases where there is traffic island that protects cyclists, especially on roads with contraflow, but does impede cars at all. Is it qualifying as traffic calming?
note that https://wiki.openstreetmap.org/wiki/Tag:traffic_calming%3Disland has no such restriction