My first thought about his parentage is that he may have been mis-registered. Perhaps he could be a sooty buckskin, if he inherited the cream gene from his mamma. I knew of a horse (over the internet, on another forum) that was basically the same colour, minus the gold spot, and genetically tested as buckskin, so it is possible despite the fact that he doesn't LOOK buckskin. The gold spot could be lack of sooty. He could even be a smokey black, genetically speaking it is a possibility with a dilute parent and a parent that HAS to have black base (or he could not be black based himself).
But I'm not a colour expert. Going to assume the dun parent was black-based, because the pali parent cannot have given him a black gene (due to being red-based, and red-based horses cannot carry black). If the dun parent was grulla, then the pali would have 'donated' the agouti gene to make bay/buckskin.