Swiss Pass Required for this Itinerary?

Don't trust RometoRio. Use the SBB website, which provides costs assuming you will have a half fare pass.

I guess by that logic all the fares on that SBB site are x2 without a travel pass?

There are so many options for passes it's mind melting to try and figure out what you are doing and if these passes are worth it. I've only got 3 trips..

I know--been there, done that! I went with the half fare pass.
The half fare card also applies to some of the the cable cars and buses, so you likely need to count more than just your point to point travel.

Along with the Half Fare Card, how long will you spend in Lauterbrunnen? The Berner Oberland Pass may be the way to go as it also can cover part of the way from Chamonix to Lauterbrunnen and full cost of Lauterbrunnen to Luzern, as well as many of the Mountain rails and lifts in the Lauterbrunnen area. You get a discount on these passes with the Half Fare Card.
https://www.berneseoberlandpass.ch/

4 days in Lauterbrunnen/Gimmewald

I guess regardless the Half Fare Pass is essential for these trips? I calculated on the SBB website that based on their 'half fare' rates and doubling it I'd be at around 180CHF for the 3 legs of the trip. Maybe I'm off or something but a 1 month half fare pass looks like 165CHF. I did something wrong maybe

A 1-month Half Fare Card is 120 CHF.
https://www.sbb.ch/en/leisure-holidays/inspiration/international-guests/swiss-halffare-card.html

Is a half fare card worth it for 4 days?
Landing in Zurich on September 24, train to Grindelwald, stay 2 night , maybe go to Lauterbrunnen and Wengen. 26th of September train to Zermatt. Plan on doing the Gornergrat train. On the 28th we will leave Zermatt for Lake Garda/Verona where we will pick up cars in Verona and stay a week in Pai.
Half fare card means you get half off the train fare? How do you know which gondolas etc it is good for?
Jungfrau if we decide to do that
Murren, Wengen ?

The Half Fare Card is worth it if you have more than 240 CHF full fare swiss tickets. The Half fare card is valid on all of the lifts in the Berner Oberland region as well as the Gornergratbahn. Validity map here:

https://www.sbb.ch/en/travelcards-and-tickets/railpasses/area-validity-map.html?layers=ch.sbb.geltungsbereiche.mvp-hta

Reinforcing what Sam said. Time after time I have calculated similar itineraries for myself and others. When spending time in the Berner Oberland, the HFC (CHF 120 for a tourist) and a Berner Oberland Pass noodle out quite nicely. Be sure to get the BORP to include your arrival and departure days so those segments arriving and leaving are covered. The HFC gives you a large discount on the BORP.

Thank you!

Some more details on Laurel's plan.

A 3-day BORP costs 150 CHF with the HFC, a savings of 80 CHF.

I would suggest the route Zurich airport to Luzern to Interlaken Ost to Grindelwald. It is a little slower than going through Bern, but is less expensive and more scenic. The HFC covers you from ZRH to Luzern. then the BORP covers you the rest of the way.

The BORP covers you to Wengen and Muerren. I you go to the Jungfrauoch, it covers you as far as Eigergltetscher, then the HFC the rest of the way to the top and back.

To go to Zermatt, the BORP covers you to Brig if you take the slower, more scenic route via Kandersteg. Brig to Zermatt use the HFC. The HFC also covers the Gornergratbahn.

Zermatt to Verona, the HFC covers you as far as Domodossola, Italy.

Hi Sam, could you also help us for passes , etc. Here is our itinerary. Arrive in Zurich August 24 for 1 night. Then take the train to Murren. 4 nights in Murren. Then train to Luzern. 2 nights in Luzern. Then train to Milan (through Lugano) on the Gotthard Panorama Express. While in Murren we may do a few short trips to some other places.