Do you provide grit (crushed granite)?
Coccidiosis wouldn't cause the grain to be undigested, it may just be passing through the gizzard without being processed.
Corid won't necessarily hurt her or the others if you decided to treat them. It's one thing I do keep on hand, but I rarely use it.
Has she been eating anything red - tomato, berries, etc.?
I do agree it looks more like coral colored urates, but I understand your concern too.
Molting can be very hard on some birds and they have a hard time. It's not unusual for them to be picky eaters during molt.
Since you have seen...