A few more thoughts after reviewing the thread -
<<"Can i combine Wengen village along with Grindelwald? How do I get to
Wengen and out of it? Can you tell me the details? How about Murren?
Will I get to see the beautiful flowers in these regions?">>
You will see a lot of snow in those regions, and, even at much lower elevations, thee is likely to be snow cover of some sort on the ground, not flowers. Flowers come in June, depending very much on altitude, since Winter hangs on stubbornly at higher altitudes, even while Spring is in full bloom at lower elevations.
In reviewing the thread, I note several questions which could be better answered by referring to a map plus the timetable (as linked by Arno).
This map is great for travel, because there is a lot of information in the menus about transport and accommodations:
Unfortunately, it does not show altitudes.
SwissTopo is full of details including altitudes, with many may options for informative overlays:
map.geo.admin.ch/?topic=ech&lang=en&bgLa yer=ch.swisstopo.pixel karte-farbe&layers=ch.bav.ha ltestellen-oev,ch.swisstopo.swiss tlm3d-wanderwege&layers_visi bility=false,false&X=1 67250.00&Y=640150.00&z oom=4
This site (Switzerland Mobility) is good for all kinds of hiking, biking , etc. and has a good map as well, with altitudes:
map.wanderland.ch/?lang=de&route=all&bgLa yer=pk&resolution=500& X=632000&Y=206000&laye rs=Wanderland
Note the menu icons art the top.
Day 4 and 5 -You do not specify where you will sleep on Day 4.
I have spent a bit of time with the timetable to figure out the journey that you describe.
If you sleep in Luzern on Day 4, travel from Luzern to Chur takes 2 hrs 10 minutes or more.
Chur to via Pontresina Tirano to Lugano: about 7 to 8 hours.
Lugano to Chur: 2 1/2 to 4 hours,
Chur to Geneva: Overnight with a 5 hour layover in Biel (as one example) taking 8 or 9 hours, arriving the next morning.
Even if you start in Chur at 0658, you will arrive in Lugano at 1441, then Chur at 1748, and Geneva at 2234 or 2247, approximately 16 hours on trains., a very long journey.
Another option to get to Geneva at the end:
The route from Luzern to Montreux ( Golden Pass route) via Zweissimmen, thence onward to Geneva, is quite scenic.
If you go via Bern instead of via Zweisimmen, it is a lot faster.
You can refine your plans by using the timetable and a map, thus answering many of your questions and allowing consideration of options.