It sounds to me like your daughter has a sensitivity to suedecloth, which is what bumgenius uses as the inner layer in the 4.0 diapers. From what I've read this is one of the more common fabric sensitivities that babies get. I would try to switch to another kind of diaper, either cotton or something that has a fleece or microfleece inner and see if her rash goes away. You didn't mention where her rash is, but if it is all over where the diaper touches her skin, this is likely the problem.

It doesn't sound like yeast to me. I am not familiar with calmoseptine but yeast rashes, once there, don't tend to go away by just switching to disposables, it has to be treated (and from my quick search calmoseptine seems to be more of a barrier ointment, not a treatment for yeast). Kids who are sensitive to citrus usually just get redness around their anal opening where poop contacts the skin the most.