Hi,
If I understand correctly you would like to add metadata to the OSM building dataset. This can be done within CesiumJs. Currently we don’t support adding these types of features for shared assets within ion. Please take a look at this issue as a starting point.
The sandcastle link in the above example is old and hence fails to load. I have modified it to work with the latest version of cesium. Please take a look here: Cesium Sandcastle
Thanks,
Ankit