I've been using ue4 for quite time, glad to see a nice scene in this engine I see you have issue with planar reflection like I had (haven't figured out why it happens) - it reflects the finger in right bottom with direct light on, while it should be shadowed. Have you solved it? If not, you probably want to avoid problematic views or replace planar reflection with screen space reflections (it has a lot of cons, but doesn't have the mentioned issue).
To avoid clutter in composition, you could either redesign (asset placements, colour contrast, detail density, it's something I still have to deal with my entry work too, since it has a lot of elements, haha). Blur could help, too bad the circle dof type doesn't let you to set intense blur, while gaussian/bokeh let you, but quality is questionable My advise trick would be making a post process material that blackens areas in specified distance from camera. So it would be like a fake shadow that covers front plane, but quicker and gives you control by how far it covers and how much darkens to make the main plane pop out in cluttered composition (post process material is basically post process, but for changing how camera "sees" view)