Can swamp eels be used for unagi like American or Japanese eels?
Despite the name, swamp eels are not true eels, and hence they are unrelated to the Japanese eel (unagi).  As far as I can tell they are also unknown in Japan and not used for food there.

That said, the Japanese kabayaki style of cooking most commonly associated with eels is also applied to any number of long, skinny, fishy creatures.  So I'd say give it a shot, and tell us how it went!