I was under the impression that translucency depends on the brightness of the polygon backface, not light proximity. As You can see in my example, the brightness on the inside is essentially the same.
Just to clarify, the Decay on the omni light is set to Inverse Square, starting at 5cm radius (that is the Pseudo area for calculating intensity decay for a point light)
The Corona sphere Light is set to 5cm radius. Intensity of both lights are the same, as one can see on the "walls" of the render.
So therefore, one would expect that the same intensity light hitting the inside of the box would produce the same effect on the outside, regardless of the distance from source.