Hi, 

v.v. liking trees showing on scree or bare rock, have I got news for you... Carto Standard does it one way and other data consumers do it their way. Look at e.g. F4Map and then zoom in to get the 3D rendition.
https://demo.f4map.com/#lat=45.9313011&lon=10.8752743&zoom=15&camera.theta=0.9

Enjoy

PS Consider trying out JOSM. Superior large multipolygon handling and validation.