Interrail France Germany Pass - Network doesn't cover train

Hello people,

I have the Interrail France Germany friend Pass and I’m having some troubles using it.
I live in Bordeaux (France) and I’d like to visit Berlin (Germany) on July 28, 2023 for a week.

From my understanding, I should use a Outbound trip to go Bordeaux-Berlin and an Inbound trip for my return Berlin-Bordeaux. Then I have 7 usable days for train travel within Germany.

Here’s the catch, the app won’t let me use my pass to go to Berlin. I must take these trains:

Bordeaux - Paris Montparnasse
Paris Nord - Koeln
Koeln - Berlin

I can activate my outbound journey for Bordeaux - Paris. They want that I use one of my 7 days for my Koeln - Berlin train. But I cannot use my pass for my Paris - Koeln train (this is the train that crosses the frontier). The app says “Our network doesn’t cover some of theses trains”.

Am I missing something? Everytime my train needs to cross the frontier it seems like I can’t use my pass.
Also, is that normal that I need to pay 92€ of sit reservation fees for my trip? I’ll just do Bordeaux - Berlin and Berlin - Bordeaux. 92€ of sit reservation on top of my pass sound a bit excessive.