Sorry Dave
The Kona interior is only available on the Lux and Premium.
The colors for the platinum is Ebony and Tuscan brown.
If you really want the Kona, I would suggest downgrading the Premium. To be honest, you aren't losing much switching between Premium and Platinum. The Platinum is pretty much the Premium with extra things like better interior with alcantera, a cooler in the center console which all takes ups space in the glove box, subtle changing on the grill, and different rims. It's up to you.
I agree, Sewell Cadillac will more likely to help you.