This does not exactly pertain to your question. On night trains in Germany (Munich to Paris, prior to it being discontinued, Frankfurt-Vienna, or within Germany) I've noticed solo young women take the night train sitting in compartments or the reclining seat. Every trip since 2009 for me has included one night train ride to max the over all days over there. None was North American, all except one (Korean ) were Europeans ( Germans and others) You sit in a compartment with 5 others, it's a toss up.
In that compartment Frankfurt to Vienna EN in 2009, I sat next to the young Korean woman, ca 22-23, who could barely speak German and English, three others were in there too. The one other time where a single woman was in my compartment was in 2010 Paris to Munich, a New Zealander, one other was there too, an Austrian. Based on what I've seen through the years on night trains esp in the summer, I would bet that Paris to Prague night route will have solo women passengers.
Usually, women on night trains I've seen do so in pairs or triples, although one of the tree others on that Frankfurt to Vienna route was a solo German woman.