Hi irSindaco.
We haven´t modified the shadedr much more, I was not able to know how to use and enable the “Custom Data 0” channel to have a custom value for the shadow strength, but in any case the value I picked is working well 
In any case, to have that shader just do what I say in the previous post and you will have it working in no time, I´m no Unreal Engine expert at all, and I barely understand UE Shader language, but if you need any kind of help just tell me.
Cheers!