Basel SBB is the border point but it isn't reflected in Rail Planner... add the journey manually I'd say.
Btw on 2 of your pass days you can travel in your country of residence. It might be cheaper to travel via Geneva.
If you'd like to take the TGV between France and Barcelona (25-35€ seat reservation), book it ASAP. Most trains in the next weeks are sold out... there are alternatives though :
- any TGV to Nîmes or Montpellier (carefully check which station as Pont du Gard* and Sud de France are in the suburbs) + regional trains to Portbou and afterwards Barcelona
- there will be a direct AVE between Lyon and Barcelona starting 13th July (not daily for now) : very convenient but not yet known if they accept passes.
Book TGVs well in advance : 10€ limited fare, then 20€. They can sell out well in advance, esp. those heading south. Check availability here : https://travel.b-europe.com/Eurail-GE/en/booking-tgv#TravelWish
Book either through the link above (4€ fee per order), on interrail.eu (2€ per person per train) or at SBB or SNCF ticket counters (no fee).
Do not hesitate for questions.
*easily connected by TER regional trains