The trick to painting white things is to make sure that almost none of it is white. All the shaded areas should be a grayish blue...or is it a blueish gray? The lighted areas are presumably lit by candlelight so they should be a pale yellowish gray. Then you place some strategic spots of pure white to make the foremost objects pop forward
Here’s the difference between murals and other kinds of art. Most artists would paint a picture of an owl, hang it on the wall, people look across the room and say “Oh what a nice picture of an owl” and that’s the desired effect.
A muralist wants people to look across the room and say “Holy crap there’s a freakin’ owl in here!” Even when you don’t actually fool people you still want to create the feeling of actually being transported to another place. Like when you're in a restaurant with a beach scene on the wall, you know you’re still in Mesa Arizona, but it gives you a little sense of escape. So I’m hoping these paintings give people a little taste of that. Not just a picture of a thing, but an illusion of the thing actually being there in the room with them.