David,
You're correct. Flynn never visited Europe. In fact, the only country he ever visited outside the USA was Cuba, a place he was very fond of.
However, Flynn's "foster father," Hugh Wilson did study the golf courses in the UK and I'm sure they had many conversations about the home of golf. Flynn was familiar with Crump and Tillinghast and probably others that studied the courses in Scotland. Yet I think it is pretty clear that Flynn was interested in developing his own interpretation of golf design, what he called modern design. He was a transition architect between the classic and modern styles. Specific shot testing and aerial demands (along with other Philadelphia School architects) were a part of a new, American version of golf architecture.