Just want to point out, My knowledge of Cesium and all is very limited, but isn't gltf just a raw 3d model file ? shouldn't it be given with some json or something to bind an element to his data?
If you’re loading the glTF directly in Cesium, you can access the JSON that defines all the primitives and nodes etc, but the way the New York example works is it’s a 3D Tileset, that includes metadata that makes it easy to click on any pixel and figure out what this building/feature is. I think the original source data was a CityGML dataset that contains per-building metadata.
In your code example it looks like you’re loading a 3D Tileset from Cesium ion. If it was created using a glTF, I don’t believe there would be any metadata associated with it. Although you should still be able to use the Scene.pick to get the primitive you clicked on.
Can you tell me about how the building position/height/name was stored in your data?