Considering props pop up in non associated movies it may just be they needed a skull for the trophy room and the Harvester was handy in the studio prop room - which would explain why the invasion isn’t mentioned in Predator 2.

I thought the multiple Jack Sparrow’s was great and indicative of Jack’s deteriorating mental state being stranded alone in the doldrums. If interesting female characters are called for perhaps we see Gibbs retired from the sea and running a tavern with a wife from the local community, but with his feisty daughter now the Pearl’s First Mate, and Angelica after the latest adventure against the backdrop of the demise of Caribbean pirating, finally capturing Jack, with his trusty com pointing to her for comedic value, and they sail into the sunset together for fresh waters.