It is possible to have almost realistic vizualization of the WEGA-B-FRAME luminaire and also correct lighting results.

Insert two 8W INDIRECT MODULES and two INDIRECT MODULES with the designed wattage in the room and join their corners. 
You should get a realistic looking WEGA-A-FRAME lamp (see image from DIALux).

Or you can use the simplified LDT file in this ZIP archive.