So i've looked at your scene. The rounded edges effect is working, but is barely visible in your scene. I think it's combination of couple things - first, your lighting is very soft and Corona RE does not work very well in such conditions, it likes when there's enough contrast between lit and unlit surfaces. Second, your radius is too big, if you reduce it to more realistic value, let's say 0,3 cm, you should get better results. In the end, you need to remember that rounded edges is shading effect and its potential is limited, it also could be that Corona's implementation could be improved, since i think some other renderers are able to achieve somehow better results. Consider adding physical bevel to your walls, as that will always be superior over shading effects. Chamfer in latest 3ds Max is pretty powerful to handle almost any kind of topology.
