The Half Fare Travelcard for tourists (Swiss Half Fare Card) is available as e-ticket. If you bought the Swiss Half Fare while logged into your account, by logging into your SBB Mobile app with the same credentials, you should see it in the ‘Tickets & Travelcards’ section.
However, if you purchased it as a guest, you can not display it on the app. You can save the travelcard manually in the traveller’s details (as Half Fare Travelcard) so that you can easily purchase your tickets with the 50% reduction. You will then have to show your Swiss Half Fare Card separately during ticket inspections. I suggest you save it in your mobile phone.
Here you will find more information.