I like Harbinger quite a bit... I edited the wording a little in the database entry to read "All other players need one more foreign colony than normal in order to win"... or something to that effect- so it doesn't name a specific number (in case people are playing 4 bases to win, or some other variant).
I would suggest adding something to the Super that maybe forces Harbinger to reveal the card when he gets it... The old Miser wild was exactly the same (win with one fewer bases), but it was changed in two subsequent publishings because people felt the sneaky win you couldn't do anything about cuz you didn't know anyone had the card was kind of a cheap way to win.