I would be very worried about taking what is regarded as Dangerous Dog in Germany, into Germany at all, in fact I would not take the chance.
It only needs something to happen,and it does not need to be your fault, and you have lost the dog,and its not like the UK , the dog will be destroyed.
As has been pointed out, Staffies have got a reputation through bad breeding and even worse ownership, and that is what you are up against.
Please do not say "But my dog will never do anything " because every dog, regardless of breed WILL do something given the right trigger,just so far you have not found out what that trigger is.