Your questions about how a retailer knows when to put release date information on their site is something that you should ask them, not us. Titles have been trademarked before without being used; what makes this situation any different? We just don't know if Suikoden Tactics is coming to america or not. Suikoden III was supposed to come to the U.K. and that never happened. There really is no point in time when we can say "this game is definitely coming to America," since we don't really know. The only time when we can say that the game is here is when it's sitting on the shelves waiting to be purchased. Things can happen in-between now and then that might delay or even cancel the release to america, and right now we don't know if Konami is bringing this game here. So, not only is the game not announced outside of Japan, but even if it was something might happen that would result in the game not coming over here, for whatever reason. So, that's two (maybe even more that I'm not aware of) big obstacles that prevent anyone from saying "this game is in America."
Don't get me wrong, I personally hope that Suikoden Tactics will come over here, but let's not be ignorant enough to say "Suikoden Tactics is most definitely coming over here" when we don't really know.