I made a batch of cocoa soap (in the lye water) last night. I'm pretty certain it won't discolor since I was working with a recipe provided in one of Jo Haslauer's books, who makes all her soaps with natural colorants and sells them commercially. Not sure about scent as I used a fragrance oil but I did notice that the cocoa water (which smelled great at the outset) smelled pretty terrible after adding lye so I probably wouldn't have wanted that scent to stick anyway. It's my understanding that natural fragrances are very difficult to achieve when it comes to soap. Shea butter is said to leave a faint shea butter fragrance in the soap, which might come across as somewhat "desserty" if you pair it with cocoa powder if that's what you want?
That is so cool. I am still pretty new to soapmaking and I'm still playing around with infused oils and replacing the lye water with other liquids. Nowhere near having the guts to add in other things like this. Your soap looks beautiful!
I've not found that shea leaves any scent to the soap. You would likely need to use a high percentage to even possibly get any carry over. I've never gone over 20%.