In FCP prefs, (not import window) are your import prefs set to leave in place? Set it that way and just drag the folders into an event. You’ll get a warning that some of the files are incompatible (txt, thumb, etc.). Click continue and you should be done. The import window can be odd sometimes. I don’t ever use it. Haven’t see the point. Ditto with legacy. I just dragged the files into the bin from the finder. Easier, quicker, and more visual.