Creating soft-edged objects without having to resort to bitmap effects is quite easy in CorelDRAW if you use the Interactive Blend tool. The following technique is useful for creating soft-edged shadows, but it can be used for many other object types (neon lights, glowing objects, deliberately blurry objects, etc.)
Important: be sure that both objects have the same amount of nodes and in a similar position, so your blend will look okay. If you want to add or remove or reshape one of the objects, be sure to delete the other one and once you are satisfied with the new shape, repeat the steps I mention in this small tutorial.