I would hazard an educated guess, that its not one of the CP series, they are known for instability in many cases.
Some people say, who have tried JWH series compounds, JWH-018 in particular, that the two were almost identical.
It isn't Hu-210 thats for sure, otherwise we would be hearing reports of bad things happening from large doses of 'spice', or at least I think so, Hu-210 is known to be very long acting, and spice is not, also Hu-210 is a full agonist (and quite a potent one) at CB1, also selective for CB1 over CB2, and I noticed similar antiinflamatory and pain relieving effects from spice, that I do from herb, although weaker by volume of plant material smoked, which are thought to be CB2 mediated.
Couldn't tell you whats in it chemically, but I can tell you its not Hu-210.
I tried spice silver, and gold, and they did indeed get me quite stoned, and I am a regular herb blazer, I believe it is largely mugwort of some species looking at the material itself, I have some actual mugwort, that I harvested myself, and it looks identical, if quite a bit lighter in color to the spice.
Identical, in the literal sense, although spice has a few black bits of something in it that look almost like tiny shreds of wood ash.