If you open up the piano roll display in the Play window, you get a lane that shows what techniques are being sent to the player. Knowing that might solve the problem.
Since “exclusive groups” etc., are not working yet, you may need to define a separate entries in the expression map for combinations like “harmonics+staccato”, etc. Try searching some of Brian Roland’s posts for clues - though he wasn’t writing about the Garritan libraries specifically.