See attachments for a theory of these artifacts being fasteners for a strap to the Sextant box. I think the theory has reasonable answers to all of these questions:
What manmade wood items were known to be at the Seven Site that could have had a wood screw?The sextant box.
Why would a strap be attached to the box?To make it easier to carry on and off the plane. More frequent loading than its original intended use on a ship. It could have been reason this container was selected to carry across the island.
(that wire pull handle seems a clumsy way to carry something long distances)
Why are there two of them?One for each end of the strap that connected it to the box
Why are there teeth?To grip the strap so the screw does not tear it or stretch the hole too much. As the strap material is forced into the “V” it compresses and gets taller, so it grips. The points of the teeth may also dig in.
Why are the teeth slightly rounded?So they don’t cut the strap
Why is there no screw in the second hole?To allow the fastener to be sewn to the strap so the teeth always point in the direction to oppose the pulling force of the strap.
Why is the hole without a screw described as "Three-lobed"?
Because an awl or heavy needle may have been used to sew it to a leather strap.
Why are the ends of the plates rounded around the open hole?So the stitching could be equal length ( a radial or fan pattern)
How could one get bent like that?Pulling the strap sideways could bend the fastener like that.
Why is there significant rotational scoring at the screws?To rotate the strap out of the way when stored. Or possibly to secure the box to the inside of the plane.
When the strap rotated, so did the clip. The screw did not rotate so the screw scored the clip (IMO more than just one time).
Why is there no rotational scoring on the bottom of the fasteners?Because the strap was under the fastener and washers between it and the box.
Why are the teeth so close to the screw?To compress the strap between the teeth and the washers below.
Note that I did not come up with this theory by looking at a picture. I reverse engineered a theory first, looking at the artifacts, and theorizing that they are related to the sextant box,
then encouraged by Jeff Nevill, looked for a picture that had the features that supported the theory.
There is a picture of a fastener that has several features that support this theory. Including being about the right size, having a screw on one end and evidence of the other hole sewn to the strap. The box it is attached to, has what looks like a dovetail joint, which the sextant box found in 1940 was reported to have.
I know it’s not logical that the Sextant box would be under the plane like that but it could have already been used latterly as a receptacle before the last flight or there were two boxes at the Seven site at one time, or Fred took the sextant out and let them use only the box for some reason. Or maybe mechanics tried to use the box before Fred stopped them.