Reloading is useful if you changed something in the library blend-file and want to see those changes
in your current blend-file without having to re-open it.
You can reload and relocate a whole library
from the context menu of the library items in the Outliner's Blender File view,
When linking objects directly into a blend-file, the Rigid Body settings
will not be linked in since they are associated with their scene's world.
As an alternative, you can link in the entire scene and set it as a Background Set.