Ja, Kuckuck-dann haste jans einfach nicht weit jenug gelesen.
Overtheborder and in fact ANY TGV canNOT be REServed online directly-either some via b-rail (pass cover nr needed-can now be gotten via new function pon site if have mobile) or call b-rail OR call SNCF. Some agents on SNCF seem to have foudn special ways to fob off all those pesky passholders by stating you must have exotic or non-available cr-crds or other invented rules. Also these cost a lot more as just In FRance only-also Sparfüchse use Nahverkehr over the border.
Jedoch: wann lernen die JUngs dies nun? IN FR and In DE its probably easiest-you are using trains anyway- to pop in at counter/Reisecenter and have them do it for you-no machine, real working people.
Profile says youre German-you re only allowed 2 days of travel in homecountry.
There is also a long overveiw of seewulf on howtodo REServ bypassing the app=cheaper too, annaB answers about every 2nd Q here with link to that-as you likely travel onward and hit head more
Overtheborder and in fact ANY TGV canNOT be REServed online directly
@mcadv Please stop repeating incorrect information. As you should know, TGV/ICE France-Germany can be booked online via Interrail. Depending on availability and the functioning of their website of course.
The best though is to book via DB or SNCF, at the ticket office or by phone.