I am in the process of my first ever DIY carpet installation, in a room that has bi-fold doors for the closet. During tear-out of the previous carpet, I wasn't observant enough to notice if the floor underneath the lower hinge brackets had carpet underlay installed, or not. While installing my new carpet underlay, I did add in some small pieces there... but now I'm worried that if I proceed this way, that once I have the carpet down over that pad, the lower hinge brackets won't line up with the original screw holes in the door jamb. (As it stands right now, if I test-fit the hinge brackets directly over the padding, I must press down on them a little to get the original holes to line up. But, my new pad is thicker than the previous one.)
I would take the little piece of pad out and place a scrap piece of 3/8" or 1/2" plywood in there if you have it. The pad will compress, the plywood will not. The doors are height adjustable, the bottom pivot in the door has threads that allow it to rise up or drop down. The original holes are not critical to keep. Place the bottom pivot guide onto the carpet and set the screw into the plywood through the carpet, the bracket may go at an angle, but press it down at the jamb end and set the screws into the jamb. Adjust the bottom pivot for height if needed.