You will have much less waste if you have the dry pellets in hanging feeders at the level of the hens' backs.
Bowls of wet mash can be put up on bricks or blocks. You can also make a stand with a rim for securing the bowls so that they don't get knocked off.
I'm glad to see that this is getting sorted out.
No healthy animal will starve itself out of "pickiness".
Personally, I never tolerated my kids being picky and I won't tolerate it from chickens. I expect them to eat anything I put into the feeder. :)
A little benign neglect is helpful here...