Yeah, the best thing I can advise is to give them brush. I'd take out a few branches, and then add in plenty of brush. If I were you, I think I'd strap a bunch of artificial branches to the ceiling, fill up about the top 4 inches entirely, to mimic bushes overhead. I'd then add a few large chunks of brush on the floor, for them to hide under.
Ditch the flowerpots, I don't think they'll want to go in those. You can give them a little 1' cube hutch in one corner if you want, but mostly they'd rather tuck under brush than go into anything, and the flowerpots are a bit small for them to want to go in. They aren't like chickens, they don't always use nesting boxes. Some quail will lay wherever they feel safe, some will build a little nest, some will just lay an egg wherever. Coturnix are kinda heavily domesticated and don't always have much wild animal sense.
How many cuties do you have? I think I see 4 in that last pic.