Hi Palawat,
currently this cannot be done.
First of you are trying to use the code for extracting the info of an object-parameter, not a wall parameter.
Second, you can use the Globals 'Wall parameters - available for Doors/Windows, listing and labels' such as WALL_THICKNESS.
However WALL_REFLINE_OFFSET does not exist (BEAM_REFLINE_OFFSET does). This has been requested at Graphisoft.