This does bring to mind some of the recent discussions of the effectiveness of certain illusions. I think the example was either Project Image or Major Image.
Project Image creates a shadow duplicate, does it duplicate scent and tremor effects? Would a wizard using major image be able to replicate the smell of an orc well enough to fool an animal with the scent ability, same for tremorsense or blindsense?
I'd begin by restricting the grimlock ability to spells that specifically note their limitation, then add other 'obvious' (subjective term) ones as they came up. To be honest though, my opinion on the aforementioned discussion probably isn't consistent.