I would totally guess at NO you COULD NOT do that, for as much as I know, Bosch is all proprietory, and secondly, as far as displays go, and Bosch, they need to be interchangable. I will take the KT display kits for example, quite popular with BMS Battery and I believe Leafbike/Leafmotor has them KT displays, is that you need a compatible controller for those as well. Now mind you KT display is quite a popular feature so "after market" suppliers of generic controllers will design a controller to hook up to KT. Bosch, No!
Mind you, on the flip side. If you have an electronics engineering PHD, then by all means you could do whatever you wanted to do, would take too much time, and too much money to be worthwhile.