Before moving upstairs past the barricade, look around in the courtroom to find a COG tag skull in one of the raised platforms there. You'll find the COG tag on top of the same tribunal platform where the skull is painted.
After finishing all enemies, you can head to the Terrace through the opened doors in the smoke-filled room and check the bloodstains on the floor in the far corner to find a COG tag.
After clearing the enemies, head to the exit but don't end the section. To the left of the exit, you should see a COG tag skull on the wall. Now head past the section's end door and check the base of the light post to find this COG tag.
Go to the lower floor and engage more enemies that will appear ahead. Once cleared, go upstairs to the left (you should immediately see the COG tag skull on the wall near the stairs) then turn left towards several trays. You'll find the section's COG tag in the corner, beside the barricade.
Once the Main Entrance is cleared, go downstairs and head to the right. You should find a COG tag skull painted near an opened doorway. Enter it and find the COG tag on the floor to your immediate right.
Once you've reached the end point of this section, go past it and you'll find the COG tag skull on the wall to the left. Go past it and go around the stairs to find some bloodstains on the floor. The COG tag should be there.
Section 7 – Plaza for the Tyran Dead
The last COG tag of this chapter is located dangerously close to Karn's starting position. From your starting position, run to the left until you see a COG tag skull on the wall. The COG tag is located on the floor almost in front of the skull.