A lot depends on when you are traveling. Assuming off season: I would start in Munich and work south. Munich has fewer “sights”, so you can relax a little more and acclimate to the time change. Rome has soooo much to see, and you will be hard pressed to see it all in two full days. Your arrival day and departure day are wasted basically. I would add a night (or more) there and reduce elsewhere.
Maybe just 2 nights in Salzburg, since it’s only 2 hrs from Munich and you could get there early enough to still see the town on arrival day. It’s really hard for me to say that, because I love Salzburg! But travel time between the other cities is greater (4-6 hrs each) and will cut into your actual time in each city.
I LOVED Cinque Terre, but that was over Christmas 20 years ago. I’ve read that it’s over-run in the summer, so depending on your travel dates you might consider dropping it and adding days to Rome and Salzburg.
Florence is my least favorite of your cities, and two nights were plenty for us. We went to the Uffizi & Duomo, shopped a bit in the markets, took a taxi to the hill across the river for views of the city. You could drop a night there too.
You could drop Florence and do Amalfi instead of C.T, but I’ve read that trains don’t go to Amalfi, only busses. You’d have to go to Naples first, either by train or plane. (I haven’t been to Amalfi, so I can’t advise on that.) Then end the trip in Rome and fly home.
For me, weather would also factor in. I hate the heat, so if the trip starts in June I would do Rome first and work north. It will still be warm in Munich by the end of the trip, but not as bad as Rome.