I've thought about this story overnight—and frankly, count me cautious about it until some other news organizations confirm it and fill in some details. A few reasons: mcclatchydc.com/news/politics-…
(1) The sourcing is relatively thin. It is sourced to two sources familiar with the matter, who are presumably not Mueller shop folks. It's not clear to me what the universe of people who would know this sort of thing from a distance looks like. 
(2) The story does not, actually, say that Michael Cohen was, in fact, in Prague at the relevant time. It says that Mueller's investigation has developed some evidence that he was in Prague. It gives no sense of how much evidence or what type of evidence—or how credible it is.
Note how the story here hedges on this point, describing the confirmation of Cohen's presence in Prague only in hypothetical terms. The reporters are being careful not to say that Cohen was actually in Prague—merely that Mueller has developed some reason to doubt his denial.
(3) It's a little too good. The Prague meeting is part of the heart and soul of the Steele Dossier. Good intel analysts need to be skeptical of intel that perfectly supports their premises, particularly when it's a bit thin. Let's show that discipline here.
(4) It would be absolutely nuts for Cohen to have gone on a campaign predicated on his non-presence in Prague if he had, in fact, been in Prague in the fashion anything like what the Steele Dossier reports. Remember, he even sued Buzzfeed and Fusion GPS over the matter.
See complaint, p. 7, para 24. It is certainly possible that Cohen is a big enough idiot to sue a media organization—and thereby invite discovery—over his presence in Prague when he, had in fact, been there, but... abcnews.go.com/Politics/micha…
So look, I'm not saying the story isn't true. And I'm not saying it won't be matched/validated by other reporting. But I'm personally going to wait until it is corroborated and fleshed out a bit before I make judgments about it.
