text: I'm not sure that " the sea polygon needs dragged into the harbour" is the right answer here, as the coastline looks like it's in the right place already.  I also wouldn't get hung up by how one example rendering displays the data (2 of the 3 renderings I can currently see on osm.org show it as water).
  Does OSM Carto (the "standard" style) really render water=salt differently to other natural=water?  Can you find another example of water=salt inland from coastline using taginfo?
  