Hi Radha -
That itinerary should work. You have done a good job of putting together the links in a logical order.
That plan has a lot of time on trains. If that is what you want, that is fine.
"Any suggestions on the Switzerland itinerary will be very helpful. We are more interested to stay there as a localite than a tourist, so we prefer to choose our base locations in villages rather than cities."
A local resident interested in exploring might choose to visit fewer places and spend more time in each of the selected ones.
And, Zürich, Luzern and Montreux are cities. Interlaken is a small city. Zermatt is a large village, with a lot of commercial activity. Wengen is the most "village-like" of the places you mention near the Jungfrau.
Ordinarily, within your time constraints, I'd chose either Montreux or Zermatt, but not both. and, ordinarily, I'd add time in the Jungfrau region. Then, for a chance at warmer climate, I'd pick Montreux. That is because the weather in Spring can often be cloudy, and it is better to have more time there to catch a good day. It is expensive to visit Jungfraujoch and you don't want to spend your money only to see nothing but the insides of clouds.
By the way, the name is not the obvious "Jungfrauhoch," but rather Jungfraujoch, which means Jungfrau "saddle" or "gap" or something similar in this usage.
"we are rather interested in off beat nature abound places, places that reflect the local culture etc. "
None of the places you have named are off the normal tourist track. There are parts of Switzerland that are not near the Alps, which fit that description. Most visitors do not want to see them on their first visit.
The famous places are famous for good reason, and the Alps are surely the first place to see the grandeur of specially Swiss nature. But, if you would like to know more about places that have fewer tourists, and are popular with the locals, I can comment about places that I often visit that are off the beaten track. Two that come to mind are the Emmental, and the Three Lakes region. Many villages in those regions are be a lot smaller, but are best accessed with some hiking. Don't know if that is an activity that would appeal. There are some nice hikes near Lake Lucerne, as well.
Let us know.