<<"Ok.. so if I buy a ticket using my half fare card and somehow make it back to the station I need to buy another ticket.
"One ride per ticket"">>
Exactly. Although you can buy a half-fare round trip ticket which gives you two rides, which will have some kind of expiration time and date.
The ticket will get you through some kind of barrier or gate, or turnstile, and will be
"punched" either literally/physically by an agent, or mechanically or electronically by the "gate" mechanism.
So, if you were to try to use the ticket a second time, it would not be valid.
There is one more subtle distinction. Offhand, the example that I can think of is for a train, but it would be true for a limited number of cableways. If the journey is between two population centers, a Swiss Travel Pass will be good for any number of journeys at any time during the validity period. The example that comes to mind is on the cograil train from Lauterbrunnen to Wengen, continuing to Kleine Scheidegg. The stretch from Lauterbrunnen to Wengen is public intercity transportation, free with the STP. The same train continuing to Kleine Scheidegg is an excursion train , since Kleine Scheidegg is not a population center (town, village, city). That part of the route is privately owned and run and maintained by a company which expects to be paid for the service and track maintenance. Although there is a discount for the STP, you still pay for the ticket. The percentage discount is negotiated between the rail company and the governments (+ the SBB, I think).
Similar arrangements exist for the cableways to Schilthorn, and in some years, the STP was 100% accepted for payment. In other years, a different deal was negotiated, and you paid/pay something, even if you have an STP.
If you have a half-fare card, you pay half fare for the LB to Wengen, and the fare set by the company for the rest of the journey. I think that they charge half fare, but they don't have to. That is negotiated with the governments/SBB as part of the franchise to run the rial line.