Small question: What armour is this?

[Watchman]

Sorry, I described it poorly, but that's what I meant. What I'm trying to get across is that these examples of textile armour, if they actually are armour, would need to show some sign of a repeating geometric design stitched into it in order for it to qualify as quilted. Just having stitching on the seams, for instance, wouldn't be enough.

Depends a bit on what you mean by "geometric", but overall more or less yeah.

Yes, there is plenty of evidence for the Achaemenid Persians employing at least some kind of quilted armour. However, this evidence disappears after the 4th C. BC. As for Alexander wearing a "soft" Persian cuirass, is that from a literary mention? Do you have a citation?

Footnote in Sidnell's Warhorse. Lemme quote it in full. "Alexander himself seems to have swapped his composite linen and metal cuirass, depicted in the Issus Mosaic, for a thickly quilted Persian one captured at Issus. Plutarch, Alexander, translated by Ian Scott-Kilvert (London, 1973), c. 32."

Make what you will out of that, can't say I've read Plutarch myself.