Linothorax vs Quilted linen vs spolas

[Archelaos]

Actually we do have. Didn't Iphicrates use linen cuirasses? Of course we are not told what the linen cuirasses of iphicrates took the place of,but it could even be no cuirass at all!

The statement that Iphicrates' troops used linen cuirasses comes from Cornelius Nepos. He was a later source, which does not necessarily invalidate his statement, but his claim that Iphicrates replaced "linked armour" ('loricarum ... sertis' - Life of Iphicrates, 1) with linen clearly does. His is the more confused of the two sources referring to Iphicrates' reforms, and his account is not to be trusted.

This quote do not invalidate Nepos I think. It is obvious that he was using earlier source, possibly greek one, so he had to translate it to latin. Full text is:

idem genus loricarum novum instituit et pro sertis atque aeneis linteas dedit.

So he replaced "linked and bronze with linen". I do not see it imposible that he found simply "thorax" in his source, and tried to explain it to his readers, or maybe he found sth like "thorax chalkeos" and tried to translate. Obviously it leaves question what word was used for "linen". It is similar to how Livius translate "peltasts" from Polibius to latin "caetrati" - this do not mean that Livius believed that Antigonid peltastai used caetra.