sounds like a bit too many.
i would do this:
moss on DW
basically i just dropped the two plants that would serve the same function of being the foreground. (you might choose the background to be planted in the middle of the bowl and then the foreground be around that main plant)
you can easily interchange the three: DHG, HC, and staurogyne.
in fact this might be interesting:
DHG midground with the DW+moss
HC at the very front of the bowl, in front of the DHG.