Let me break this down into a much simpler and more direct argument. We have ways to very reliably identify the elemental composition of any material you can i

Let me break this down into a much simpler and more direct argument. We have ways to very reliably identify the elemental composition of any material you can imagine. That doesn't tell us how to manufacture that material, but it does tell us what it's made out of. These are extremely robust techniques (x-ray diffraction and x-ray fluorescence) that work on anything made out of atoms. The claim, any claim, of an "unidentifiable alloy" is simply not credible without presenting x-ray fluorescence and x-ray diffraction data to back that up. It is infinitely more likely that no one examining these materials had such instruments available to them, so they just sort of shrugged and said "I dunno what it is" which then got telephone-gamed into "unidentifiable alloys!" along the way. Extraordinary claims require extraordinary evidence. This is an extraordinary claim with no evidence. So it is not a credible claim.