Tried to import a file without an extension. Since it wasn't recognized, I couldn't import it, not even manually choose the file type. That is a bit odd.
In my specific case I knew it was a tab separated file, so I changed the ending to tab (since that is what the dialog box suggests), but still, though recognized as delineated text file, it suggested comman and not a tab. Also odd, evn though in the end I could import it.
Would be nice to change this behavior.
Finally, it would be nice to have preview of data next to the "fields found" window.
The Knime node "File Reader" is what I see as a role-model in terms of previewing your files and correcting anything before proceeding any further, see below.
But maybe I simply missed something?