Evidence for legionary vs auxiliary helmet patterns

[M. Demetrius]

each legion may have had their own manufacturing patterns/styles.

While we can't go too far with this as a base for reasoning, if that were so, then the style would be similar because the immuni (~speculation~) in the "Galea Fabrica" would make them how the head armorer indicated. Same artist, same art, so to speak. The general form would be the same as the helmets being produced anywhere during that time, but the specific details would be unique to the craftsmen. Is that reasonable?

No, I wouldn't tell the public that was so at an outreach event. Too much thinking, too little reference in the record.