From your linked map it looks like Basel BdHf is in Zone 8. I highly doubt that the you could travel from Zone 2 to Basel BdHf with just a GA and Zone 2 ticket.
For your mind, get a written statement from a DB and SBB official that clearly state that your tickets are valid for the intended journeys.
I know for sure that the same thing applies inside Switzerland between different ticket areas. A crossing between TNW and A-Welle or A-Welle and ZVV is not possible if the traveler has two tickets for each area. It is in Chapter 9 of the
T600 - Allgemeiner Personentarif SBB