How did you add the layer of darkness can I just ask. Because it seems that it’s uneven between the foreground characters and the background scenery, as if the characters are lit by a different light source than the rest of the pic. What I would suggest is using the dark-> light gradient circle (rather than the light-> dark gradient circle used for shading/ highlighting) and remove the 2nd colour and place it so it covers the whole picture as the top layer. If you then experiment with the placement you can get some really interesting atmospherics that look natural on both background and foreground at the same time and still work with shown light sources, such as the light in the background.
Hope this is helpful. Keep up the good work.