Yes it would be very interesting if we could find the bosch part numbers. It must be availabe somewhere as it is built into Polo E-Flex sold in Brasil. The good news is that we know now that in a multipoint injected engine heating the fuel should be enough for cold starting
I think there probably is some kind of temperature sensing in the system. In the youtube film you can see an instrument on the dashboard at min 1:10 that -unless it is a simple timer- indicates the fuelrail temperature, and when the car is ready to start with a key symbol!
Fast heating diesel glow-plugs are also self regulating but of course set for a much higher temperature. Here are current and temperature graphs of three types of NGK diesel glow plugs:
If the current flow already changes enough between 10 and lets say 100 degrees, a controlling device maybe cold use the dieselplugs/heaterplugs primairy current for determing the fuels temperature and not need an extra temperature sensor but use the current flow as a virtual temperature sensor.
Another option is to put the temperure sensor inside or very close to the injectors I think that would be the best solution. One could use pulse with modulation and diesel plugs to quickly heat the fuelrail to the desired temperature.
The e-flex system must also know when there is gasoline in the fuel because the fuels boiling point is lower and in that case less or no heat at all is needed.
Greetings Aryan