As a 3D modeler, I know that objects have characteristics which are usually adjustable in a 3D modeling software, such as color in the materials or ambient lighting in a diffuse applied surface. I have actually adjusted the light literally thru the 3D or 2D object by making changes which are available in the modeling software. When the modeler makes the setting, then the changes are recorded in a file included with the model in the model folder. Some game engines allow the modeler to also change type and amount of shadow by using the modeling software and/or an SDK included with the game engine. The most common thing that I have seen is some kind of configuration file which the game engine writes (such as xml or a conf.ini file) that can be manipulated directly, with 3D modeling software, by the game engine SDK, or all of these options may be available. This can be for shadow, as well.
Unity3D is fairly well documented. I am sure that there is a module in the coding which you may customize for this sort of thing. Perhaps you need to write an exception so the game engine knows when it should apply your coding to the scene. Not to be mean, but it can't read your mind, if you know what I am saying. I am sure that there is a prescribed way in Unity 3D for coding your own shadow and lighting effects. It might not be exactly by industry standards if they wrote their own library for it.
Personal life and your private thoughts always effect your career. Research is the intellectual backbone of game development and the first order. Version Control is crucial for full management of applications and software. The better the workflow pipeline, then the greater the potential output for a quality game. Completing projects is the last but finest order.
by Clinton, 3Ddreamer