Adam Szalai Hungary
I think most of your questions have been addressed in => this discussion last week, especially in my post at the bottom.
In your situation, a Half Fare Travelcard is cheaper than 3 Swiss Half Fare Cards. But you need a Swiss (accomodation) address for the delivery of the physical SwissPass card, which takes about 10 days to get produced and delivered.
Note that you don’t need any half fare card/pass for BUYING tickets, as this is NOT checked during the purchase process (also if purchasing from vending machines, which do not authenticate you)! The half fare card will only be checked while TRAVELING in a train during a ticket control, as a proof that you’re entitled to use discounted tickets instead of full fare ones.
Only the (1-year) Half Fare Travelcard can be “linked” to the SBB Mobile app via your SwissPass account used for login. The Swiss Half Fare Card comes as “standalone” electronic document only.