we're trying to work around the fact that you cannot currently directly | geom in Maps +
So what we're doing instead is a multi step approach:
We geom our original feature IDs from a set of KMZs
We create a lookup, transforming the original "[[...][...]]" (multi-)polygon notation from the first step's result to the semicolon-separated notation that the definition of a feature requires in Maps+
We run our actual query and get the features from the lookup
Now the strange thing is: Step 1 always seems to return complete polygons, because they render just fine on a Choropleth map.
This happens sort of 'in the background' though, as the polygon definition is never fully displayed on the statistics tab.
Because of that, we don't have the neccessary data to approach Step 2, as we'll only get like one or two points written to our intended output field.
The app is not currently compatible with the geom command. You can use your KML/KMZ files directly to add the overlays onto the map. The only caveat is that you'll need to copy those files into the app to reference and serve them. See the docs on KML/KMZ overlays.