Hello bellabella
First of all, I would like to inform you that we also have an English SBB community. Maybe someone has the same question and comes across your post. Next time, just change the language of the page to enter the English SBB community.
Yes, even without a Half-Fare travelcard, you can still buy a saver offers, unless otherwise stated. Supersaver tickets and Supersaver day passes can be purchased without a Half-Fare travelcard on sbb.ch or the SBB mobile app.
Have a nice day.
Greetings, VlaznimA.