Yes, it's just trial for JOSM function for copy data to OSM. We'll remove on next step when following the Guidelines. Second, Data Sharing Agrement with the city government (data ownership) is on going.
Thank you! Minh

Thank you, Jan.
We're trying to update admin boundary. These keys are in original data and we will change as it reflect admin relations.
Cheers, Minh

Whatever it is island or islet, it does not include territorial sea (12nm from coastline). OSM did not update the map at zoom level 12 and it's still there.