hopav , thanks a lot for your inquiry.
"Color in Ray-Traced Sun Shadows
When Ray-Traced Sun Shadows are enabled, semi-transparent geometry is now casting shadows with the opacity and tint color contributing to the appearance of the shadow. This feature is a work in progress."
Otherwise without utilizing ray-tracing these kind of (colored) shadows cast by semi-transparent surfaces are not available, mainly due to technical and performance limitations.
Let me know if any further questions comes up of course!