I think 4 places is too many for 12 days. You’ll spend a lot of time packing up/moving and less time actually enjoying the sites. Switzerland is extremely well connected by public transportation and day trips to places are sometimes easier than moving. I’d suggest 2-3 spots and if you run out of things to explore in that area (doubtful), then you can do a day trip.
For example, from a base of Luzern you can do multiple different boat and mountain excursions, explore the historic city + do day trips if you’d like to both Bern and Zurich. But to accomplish all that, you’d need at least 4-5 days in Luzern alone.
Some popular areas to look into are Luzern, the Berner Oberland Region (staying somewhere like Wengen), Montreux/Lake Geneva, Zermatt and eastern Switzerland (St Moritz, etc). You can’t cover all that in 12 days, so I’d recommend watching YouTube videos, reading blogs and posts here and narrowing down what feels most exciting to you based on your personal preferences.