Never could see the point of that type of system with the cables and motor, just seems to add unnecessary complication? Luckily I have Vag Com so would use that if I ever have to do an electric one.The citroen electric hand brake is just like a manual one, there's a big motor unit in the spare wheel well that pulls the cable like the old handbrake.
My brother had an A5, and left me confused at first looking for the handbrake cable. The new vag ones with motor on the caliper are easy to do too. 12v battery on the connector rewinds it then use the tool. The electronics have a fit when you start the car, but once it's operated twice it's all good again.