I am not familiar with how this object is referenced in the API, but the bounding box that you are snooping with the lookup tool is probably the arrow (the annotation itself). There may be a better way to do this, but I believe that you can pull the ViewSection object from the arrow element via the GetDependentElements() method.
That being said, the placement point that you are looking for might actually be the Location property of the ElevationMarker that the ViewSection was created from. In your example, the ElevationMarker is the circular marker. Hopefully someone else can expand upon this, but I believe that the origin of the transform of the BoundingBoxXYZ of the ViewSection is not really related to the placement point of the ElevationMarker object.