This is jEdit5.2pre1 on Mac OS X (Mavericks) and Java 7u55.
The action set-view-title has no effect. (It is the first time I see this feature, so it is probably of little practical relevance.)
What is interesting is that the string (initially "jEdit") does show up in the window title on Linux, but I do not see this string before or after I rename the view title on Mac OSX. I am not sure if this is a bug though. The fact that we see the string at all in KDE is probably a "feature" of KDE.
I doubt there is anything we can do from the jEdit side about this.