2. A jet of any kind, invisible or not, is a high tech piece of gear. Its more than a little bizarre having this show up from a non-technological society. Now, sometimes Themiscyra has plenty of technology. . . but most versions lean more heavily towards Greek myth and magic. If Themiscyra is a non-technological island where everything is handled via bronze age tech, innate superpowers, and magic? Your not going to have
an invisible jet coming from there.
Or basically, the issue isn't the plausibility of a jet turning invisible. The issue is the plausibility of how the amazons ended up with one, and whether it fits with their style.