Dear Great Man,
Welcome back to the Wefugees Community and thank you for your question.
As fas as I know (and it is also written on this website by the authorities in Berlin), a travel document may not be valid for a longer period than the residence permit that was issued or will be issued. However, I am not too familiar with your personal background and why your residence permit is only valid for 6 months. As the application for the travel document also comes with fees, the immigration office may not issue it for a shorter period than 1 year. But that is only an assumption.
I will link two of our experts here. Dear @manrhei-mbeon or @mbeon-fardeen, can you share some experience or information with us?
In any case, please don't hesitate to get back to us with any further questions.
All the best,