Basically yes.
The game can only save what is known to it at the point when the save is done. For all that is stored in the save already, the game ignores any changes you make. (Stats like STR, DEX, ... skills, talents, etc. for characters are stored in the save if I remember correctly, so they no longer get picked up from the stat files.)
Since the vast majority of objects (almost all characters, some items) are in the game at the start already, you have to start a new game for changes to take effect.
In the new game, all objects will have the changes.