It seems that the forward navigations in the test application confuse the delta submit calculation on the server side. For the client nothing indicates that the JSF view has changed (due to the non-redirecting navigation) thus the previous parameters are preserved and used normally just like during any DOM update. On the server-side though the view is completely swapped with a new one, since the previous parameters are saved as attributes on the form components they are lost during the navigation. Because of this the client and server delta submit data is out of sync.
This issue occurs also with icefaces2/trunk fro me.