That transform in the JSON file. I believe that is the local ENU transform for that location. Yes, it is, If I place the camera near the house and type this in the console (EDIT: reading back on your previous post I should have known!)
Cesium.Transforms.eastNorthUpToFixedFrame(viewer.scene.camera.position, viewer.scene.globe.ellipsoid, new Cesium.Matrix4());
I get that transform. So the modelMatrix position apparently is transformed by that transform. Hmm, now how to rotate it. My rotation attempts should have worked, where I tried to rotate 90deg in either direction. Those new rotation vectors should have been transformed just like the position vector was. In any event you should see the house, even if at a funny orientation.
Try replacing the transform in the json with this. I took the one that’s there now and rotated it 90deg around it’s up vector. Possibly it’ll rotate the house 90deg, who knows. (corrected, first time I rotated 90 radians!)
[
0.5719022525624771,
0.6163388209036162,
0.541344904867667,
0,
-0.7979626193589172,
0.2649554064190438,
0.5413449162659866,
0,
0.19021961055045852,
-0.7415693387513873,
0.6433439241941505,
0,
1214931,
-4736397,
4081525,
1
]