To not spoil it too much, try reading the code again and see what exactly you have to do in terms of how you move the camera and what that does to the player. You don't have to edit any code.
Hope this helped :3
Solution below:
Move the camera so that the floor is covering the player and it turns into that black and white dot grid. Then you will be able to walk through the transparent walls.
For the gold bugs, stand in front of the bugs wall and move your camera so that it is in line with the floor, then move it left until the corner of the main is covering your entire character.