Multi city rail advice for Europe in early June coming from the US

My wife and I are looking to fly from the US (Boston) to Paris early next June take a train to Munich then to Salzburg staying 2 days in each place and then onto Ljubljana for a week or 2 and fly back from there. I know it is not much time in each place, but wanted to at least experience these other countries. If this sounds unreasonable could just fly into Slovenia and skip the rest. May also rent a car while in Slovenia and do a day trip to Italy and Croatia if we have time. Really into cycling and hiking and have been exploring our options there as well. Thanks