It seems to me that if the smell of chocolate is part of the desired experience, you design and render that smell. Random link on artificial smells: https://foodbabe.com/2015/02/16/the-behind-the-scenes-market...

What kind of chocolate smell do we want? How sweet? How much vanilla note? How much burnt component? How concentrated or diffused in space? We probably don't want the smell to change over time, just like you probably don't want the colors in a painting to change over time.

To me, making the artifact out of chocolate is a bad way of creating a chocolate smell. The exposed surface area will offgas and oxidize, resulting in a diminishing and changing smell. It seems lazy; it also seems like "confusing the map with the territory".