How to draw squares, plazas etc.

How to draw squares and plazas when they not fit to any single physical object?

There are very accurate data about streets, squares ect. in my town, town hall provides data as wms server with layers which I can use in JOSM. Problem is, that squares often does not fit to any single object, they can contain for example few parts of different landuses, few parts of roads and even few buildings. I draw polygons and tag them like: area=yes, name=Some Square, source=some town hall. It’s surely bad way, it renders on the map (or not if collide with another name), but the worst thing is, that it does not appear in search results.

How to solve this? Should I force drawing polygon to fit physical object (one landuse and name for example) or is there any way to use accurate data from town hall?