An interesting thread, and an important clue provided that the Sextant Box was from the Bushnell. Which leads me to an alternative hypothesis to explain some of the "7" site findings.
Suppose the Bushnell survey party on that part of the island did not leave the island every late afternoon to go back aboard ship. Because this particular crew was on the far side of the island, they stayed overnight at least one night near the 7 site. They knew this ahead of time, and brought a cask of water (chain and stopper), a Benedictine bottle, along with other items. They augmented their evening meal with clams found in the lagoon, along with birds, turtles, etc, accounting for at least one of the camp/fire sites. Having drunk the Benedictine bottle, they leave it behind. They inadvertently leave the Sextant box.
They fail to see/smell the prior camp/fire sites left by AE and the corpse/bones, easily enough explained by poor visibility through the bush and the survey was focused primarily on the lagoon and ocean shoreline, vice the interior portions of the island.
What I am proposing is that not all of the items purportedly ascribed to AE at the 7 site are hers, particularly the Benedictine bottle and the western style of clam openings---these may well be due to the Bushnell survey party. This situation is the classic archeological problem of just a listing of items found without proper context and location information.
Just throwing this out for discussion.