problem of using my own building tileset

hello, I m trying to make an offline city with plenty of buildings. the city is in China.

i tried all providers (SRTM , Bing Maps, SRTM 30, Map box, Arcgis), they all not providing enough build data, say, in many city maps in China, just few building showed.

But if i use Chinese Maps provider , say, baidu maps, amap, they provide large sum  of city buildings.

and then i downloaded the KML file of the building data, imported to mapbox studio , it works correctly. as you can see the attached image, the red buildings are mapbox data, the blue building are my own data.  The red buildings amount is very less.(Arcgis does the same）

and, i made this tileset file as Public data ， so that it should be access for everyone.

but when i build this area from real world terrain, it can not get those blue building, only gets the red building.

so, is there anyway to solve this? say, i already have all building data in   KML format (i should be able to get  any other formats, if necessary) , it is possible to generate buildings from unity editor?  or do i make anything wrong?