While Rome2Rio is a great tool for initial research, you should never take it as authoritative, and never book from them. Instead, use it to direct you to the actual operator of the flight, bus, train, etc, and book directly from them.
You've already been given good advice for your Italian trains. For Switzerland, with 7 days you will probably want some kind of pass. The choices are a Swiss Travel Pass, a Half Fare Card, a Berner Oberland Pass, or the Jungfrau Travel Pass. If you're not going to be in other parts of Switzerland, the Jungfrau Travel Pass is probably the easiest and best deal for a Grindelwald-based trip. Details here: https://www.myswissalps.com/jungfrautravelpass
The Berner Oberland Pass covers a larger area, although it has different coverage than the Jungfrau Pass (some things that are fully covered with one are only discounted or not covered with the other). Details here: https://www.myswissalps.com/regionalpassberneseoberland/validity
The Swiss Pass covers the entire country, but it has only 25%-50% off the trains above Wengen or Grindelwald, so it's less useful than the Jungfrau Travel Pass for a Grindelwald-based stay.
The Half Fare Card costs 120 CHF and gets you 50% off of anything that moves in the whole country. Advantage is that if you're taking more than 240 CHF of transit, you can't lose (so no complex calculations). Disadvantage is that you have to buy tickets every time (not hard, as all machines have a "Half Fare/Child Fare" option for every ticket). When using a Pass, you only have to buy tickets for items not fully covered; for everything else, you just hop on, and show your Pass when asked. Technically, you have to show your passport when using the Pass; this is rarely asked for, but you should have it handy just in case (fines are very high for breaking the rules in Switzerland).
Yes, it IS complicated to figure out the best option. But any of them are likely better than paying full fares each time for a 7 day stay!