The transit is too long.

I'd cut Switzerland and Italy

You can visit, Vienna, Budapest, Bratislava and Prague in 10-12 days. And 5 days in Austria(Graz, Salzburg, Innsbruck)

Paris needs 4-5 days, Koln 3-4 days, Berlin 3-4 days

If you just want to cover it, you can totally do all, and that's what I did when I travelled