I've pondered over this quite a bit, myself. I only have three possible assumptions, and perhaps one day we'll see which is right. Here they are in the order of increasing likelihood:
At first I had assumed that everyone in the Circle of Knowing was an Archon, and that crazy spriggan girl's assessment of Archons was at least somewhat right on. However, it's still possible that only Louisoix and Urianger are; they're the only ones with facial tattoos, and the word Archon isn't even breathed around the others unless in reference to the other two, and those two are referred to by the title directly, "THE ARCHON Urianger" and "THE ARCHON Louisoix"
- This is a very old leve card, the very same one taken to fight the marbol. It carries this powerful memory on it. (Not likely, as it's a Limsa Lominsa leve card. But you never know. Maybe the faction'd it out.)
- A member of the 10 Years Ago Party was recently at The Drowning Wench and decided to see the available quests. Upon seeing his card, he had a flashback to this powerful member, which was then transferred to the card, which then triggers the Midlander's echo. (Little more likely, at least sounds possible.)
- A member of the 10 Years Ago Party is right behind the Midlander having a drink and he never realizes it. (The only thing that seems to directly follow the lore.)
As stated above, the Hatching-tide archon summoning was purposely stopped by a hooded woman with a male associate ... Y'shtola and Thancred preparing for the arrival of the true Archon(s)? We know Papalymo and Ypa are often doing their own thing; and they're not so much people of consideration as people of talent. They don't say anything profound or come to any great conclusions (though they are well-informed), but come the first showdown with Gaius van Baelsar, she's the only member of the party who manages to land a blow against him.
Also I just noticed that the translation of the Hatching-tide post says SKYkin and not CLOUDkin when referring to that dodo. SOMEONE'S IN TROUBLE.
I'd assume they all have to have names, and it's been driving me nuts not knowing. It's just a matter of IF A THEN B. These cinematics have scripts. How do these scripts differentiate between them? Does it say "THE MIDLANDER SAYS" and then "THE ELEZEN REPLIES" (much like my own lore write-up)?
It would be interesting if it did mention clans labels, because the clans aren't represented canonically. This cinematic was made at a time when the subtle differences (ear size, war paint, pupils) were not decided on, but there was a clear binary* (even clearer than we have now). This binary was made a little less black and white over time, and the CG members do not reflect this. These elezen have giant ears, something that only the Duskwight should have, but they lack the blue complexion and tattoos associated with Duskwight at that time. The miqo'te has the complexion and pupils of a Seeker of the Sun but the warpaint worn by Keepers of the Moon.
However, you have to admit, they might just have silly everyday code-names around the office. The script could just call for Hiroshi and Akira to do this while little lalafell Reiko does that... While this doesn't seem likely with SE's depth of lore, it's still possible that they had a conversation equivalent to, "What do we call them in the script?" "I don't know. Bob? He looks like a Bob." and then flash forward to planning The End of an Era, "Okay, Bob's gonna do Steel Cyclone."
* See below
Duskwight = Blue, Wildwood = Tan
Sea Wolf = Green, Hellsguard = Red
Seekers of the Sun = Tan, Keepers of the Moon = Blue
Midlander = Scrawny, Highlander = Stacked
Plainsfolk = Fair/No Gems, Dunesfolk = Tan/Gems.