I talked to my son a couple of days ago, and his package with the cookies arrived in Vanuatu. Actually, it arrived two days after he and his wife had left for a two week stint to another island, so it was two days short of four weeks when they got back and actually opened the package. He said the cookies were still sealed up and fresh.
So I opened my cookies, the ones I had vacuum sealed and saved to open when they opened their package. They were okay, but would have been much better had they arrived before their trip! But when you're that far from home and familiar tastes, just about anything tastes good, they assured me.
The vacuum sealing made them a bit flat, so I'm going to try something else with the next cookies I send.