I think you would have to somehow convince your CIC to use the harness aux input instead of the MOST aux input... I'm not sure if the CIC has that as a separate coding option, but you'd basically be partly telling your CIC that you don't have a combox.
I'm curious what sound quality would be like going from the carplay box to an AUX->MOST adapter (there are a few different ones:
https://www.aliexpress.com/item/4001227997684.html )