Kerouac - to be honest I haven't carried out systematic comparisons between using pure curry powder or the same powder mixed with additional quantities of certain spices. It just seems to me that if the mix powder has more depth of flavour, or was in any way, better - then the curry powder manufacturers would do the same thing. But they don't. For that reason, I believe so-called mix powder is inferior.
Going back to your original query, if you want to try and produce a creamy curry with coconut, then try the korma recipe I wrote up about 10 years ago, based on inputs from Ghanna, another member. The proportions are spot on, rather than adding too much cream, as you may have done. Actually, Ghanna's recipe uses evaporated milk in place of cream. In my opinion, it tastes better.