For the wall thickness is around 4", I assume the wall is solid or fully grouted. The suggested repair procedure is as indicated below:
Excavate and expose the entire hole.
Thoroughly clean the surfaces of the exposed hole and remove any loose particles.
Form the back of the hole. This is tricky if you do not have access to the crawlspace, or it is ...
Sounds like you get a fair amount of rain.
What year was your house built? A modern foundation would either have damp proofing or a dimple membrane applied to the outside of the foundation wall.
I'd dig the wall, wire brush the area, and parge at least the one defect area with mortar or dry pack. I'd then install some delta MS or other dimple board to ...
Apparently the hole does not cause a strength problem . Concrete does not bond to old concrete, it mechanically interlocks ( with the right configurations). I would foam -in-place with urethane foam. It comes in a spray can and is often recommended for thermal insulation. It will expand to tightly fill any shape opening and sticks to everything, such as ...
Try rock anchors drilled into bedrock, either epoxy in or a Hilti rawl.
You can carry out pull tests which will give the force needed to pull out the anchors. This should then be enough information to see if the bedrock is strong enough to hold down the structure and how many anchors will be required.
This should be a lot cheaper than the concrete beams ...
Lay heavy landscape fabric or galvanized hardware cloth and rock under the entire area.
Leave the space open enough that it doesn't appeal to den-seekers.
Install a skirt and place a row of pavers or large rocks around it.
Install wire mesh down to the ground and then outward a foot or so. Cover it with skirting and landscaping.
Install wire ...