There is a steel plate that bolts to the block and is where the motor mount attaches. The timing cover seals to it. It takes the stress. There should be little or no load on these bolts and the timing cover. The purpose of the holes that are broken is to allow the two bottom bolts for the timing cover to pass through from the inside, a dumb design. You can see the weld nuts on the two bottom timing cover holes. This makes it mandatory to remove the pan to get to these bolts before the timing cover can be removed. If I remember those holes could be tapped to the next size without even drilling. Then bolts can be inserted & removed from the front with the pan in place.
From the looks of your cap I think someone tried very hard to remove the cover not knowing about the bottom bolts. Were the broken pieces in the engine? Did someone reassemble the engine this way.? The bolts passing from the inside would still hold the timing cover. Sealing the pan gasket is really the issue. I think these caps but it could still be welded up if there are no cracks running to the bearing area or the cap bolts. I have a friend who could weld it. A simple fix would be weld nuts on the back side for bolts from the front and form the gasket area with JB Weld. It will work and the "know it alls" will never see it.
