Synthetic Stucco is a light weight Stucco system applied over Expanded Foam board & will have a very hollow sound when taped on. Conventional Stucco will be very hard with a very solid sound when taped on.
To cut a channel into a Synthetic Stucco is very easy & repair is not as difficult as cement stucco. Also the substrate that the Stucco is applied to will affect what method is used to cut the channel into the surface.
I think your best bet would be to do the routing of the wiring from the inside.