skull halo 2

can the developers add the missing skulls like the scarab gun skull and the feather skull as well as the Boom skull

Hi everyone! I find a option in Advance Settings that activate the skulls in game, my question is I need to find every skull in the levels or i can activate the skulls without get them? I activated IWHBYD skull but i see no difference Thank u very much and have a nice day :)