Creative freedom and passing

If I set my teams passing to short and their creative freedom to high, will my team continue to pass short?

Yes, but you'll probably (not always) lose some possession %. CF set to high will allow your players to try the more unexpected. If these players have high Flair and Creativity along with decent Decision then they'll likely allow you to unlock a defence that you might otherwise have difficulty with. In exchange you might lose the ball more often and perhaps in a dangerous area (again not always, depends on Mentality settings as well). Everything is a tradeoff. Also this depends on where you start. With Very Rigid or Rigid philosophy you start off with CF at relatively low levels. At Fluid and very fluid, CF is already quite high across the board.

My advice is to keep things simple. The different philosophies alter CF, Mentality and Closing Down for all your players, keep this in mind.

Save the game and Play one game (all default settings or the settings you want such as short passing) at very Rigid or Rigid . Go back and play the same exact game this time at Balanced. Again go back and then again at Fluid. Watch the games and see how your players play each time. You can then try again the same process with another game. I know this will take time but you'll learn a lot about what works best for YOU and YOUR team.

Once you figure out which one you like best you can then fine tune certain settings for certain players.