You're correct it's a hybrid, but I tend to shy away from this term, at least here in Germany. This is also one of the reasons for placing the generator in a trailer. If the unit was integrated into the C5 there is a possibility that the "Bulls" or the TÜV (MoT) come to the conclusion that if it's a hybrid then it's no longer a bike but a car, after all we've never heard of a hybrid bike.
As a car they have no documentation covering the C5, so the only solution would be to ban it.
I once tried to obtain an operational permit for my Piper P2 from the TÜV, they informed me it would cost a minimum of 15,000 Marks. At that time you could buy a Mini for 5,000, or an E-Type for 18,000.
So I'm not even going to try to obtain a permit for the C5. One other problem in Germany is that each State has it's own TÜV and they are not unified, they make up their own regs. E.g. in Bavaria 6" wide wheels are not permitted on a (old) Mini, in Baden Würtenberg they are. Net result the Bavarians go over the border and have their wheels registered there, absolute nuts.