Exactly what it says. It's pretty much something that came to my mind recently. Now, it does involve some speculation here and there, some of it leaning on trivia, but's it's pretty much just a thought, not a downright theory.
Now, what is that thought? Well, the CRDL trivia on their page here says they could be seen as a foil to RWBY, though I don't agree with it entirely, due to the reasoning feeling weak due to oversimplicity (4 girls - 4 guys, heroines-bullies). If anything, I felt they were a foil to JNPR instead. To be more precise, each member of CRDL could be seen as a foil, of the "opposite yet similar" to a member of JNPR, more than they would be to RWBY. (Leaving out personality comparisons due to how little we've seen them):
1-Cardin, foil to Jaune. His allusion is the Cardinal of Winchester, who presided over Jeanne D'Arc's trial. And Jeanne D'Arc is who Jaune Arc alludes to. Design-wise, both look like Knights of sorts, though I feel the need to point out that besides using a darker color, Cardin's chest armorshows upfront a symbol, that of a bird. Meanwhile, Jaune's chest armorhides his symbol (which btw, is likely a rabbit).
Combat wise, they both use extremely-simplistic and classic weapons, a Sword for Jaune and a Mace for Cardin, and both add just a very small amount of tech to their equipment (Cardin's Mace has Fire Dust, Jaune's shield can fold into a Sheath). Aditionally, both are the leaders of their team, even though they were not good choices for it for X reason back then: Cardin because he outright embraces Friendly Fire and Anti-Teamwork, Jaune because had 0 experience whatsoever.
2-Dove, foil to Pyrrha. Unlike Cardin, the rest of the team has no confirmed allusions, though there are some hypothesis here and there. Thus, this is the part where the mentioned speculation appears. Now, Dove, has as been suggested previously on the internet, probably alludes to Hector. "Evidence" for this is that Hector was Troy's greatest fighter, same thing Achilles was for Greece.
Fittingly, both Dove and Pyrrha show the most skill in combat on to their teams, and indeed RT even mentioned that was the case with Dove. And more than that, even though both are the most skilled/experienced members of their respective teams, they are both NOT the leaders of said teams. Weapon wise, their weapons are also foils: They both use gunswords, but while Pyrrha's is a sword that turns into a gun, Dove's is an actual gun-sword. Aesthetically, both also wear a good deal of armor (but granted, that part is pretty weak; 3/4 of CRDL does, even the same design, for whatever reason).
3-Sky, foil to Nora. Now, Lark has been less outstanding than either Dove or Cardin. Indeed, he may be the least developed, and that's saying something within CRDL. But he still has some things worth comparing with Nora. Now, who would be his allusion? Judging from the idea of CRDL being "Nemesis" to JNPR, it would be Loki. Of course, he has been so insignificant that this is questionable. He hasn't shown any real Loki-like trait or evidence to suggest it.
He still has at least 1 thing to compare to Nora though. First, it's the fact that both are the only members of their team to use Polearms, yet while Nora's is an Explosive and Crushing Weapon (Grenade Launcher-Hammer), Sky's is a Piercing and Hacking weapon (Rifle(?) War-Axe). Both also seem to put more emphasis on Strength over Skill in combat. And that's more or less it, thank you RT for giving this guy so little character.
4-Russel, to Ren. Now this may seem weird to you, but please understand, there's a reason I'm saying this. First of all, who does he allude to? It's been hypothesized that he was supposed to allude to Robin Hood, at least originally. I believe it was for meta-reasons, due to his originally-planned name: Russel Crow, and how the actor Russel Crowe played Robin Hood. Your mileage may vary on that, but I do feel Russel's design evokes a Rogue imagery pretty well. (Unlike Robin Hood though, Russel is no Archer).
Now, as you can see, if he alludes to Robyn Hode, he breaks the whole "Nemesis of JNPR" theme, for Robin Hood has nothing to do with Mulan, Ren's allusion. But then again, so does Ren with his team, in a sense. Joan of Arc, Thor, Achilles, all 3 are from Europe, but Hua Mulan, is Chinese, thus breaking a small theme within his team, in a way.
When it comes to the allusions, you could remark on a few things though. Mulan took her father's place as a soldier, while Robin Hood was an outlaw. They both are legendary figures, in the sense that neither has concrete proof of having truly existed, they were both considered more as Legends than historical people.
Design-wise, both Russel and Ren have the least amount of Armor of their whole team. They also both have 2-colored hair (Grey-and-AppleGreen for Russel, Black and Pink for Ren). Combat-wise, they both show great levels of agility, the most among their respective teams. They both Dual-Wield their weapons as well. Now, you could try to also add that they use similar weapons, though it depends on if you see Stormflower as Dagger-like, and assume Russel's daggers are also guns.
I assume you could try to find some "opposite-yet-similar" traits between CRDL and RWBY as well, but at least for now, I see more Foiling between CRDL and JNPR, than I see it with RWBY.
I'm pretty sure it's not there... I own the commentaries on the Dvds, the only places it could be are RTX's and other Q/A's, extras... unless you are refering to when they said "the ____ isn't his symbol" I know they said a few aren't, they just never said what is in a commentary however.
Edit: I saw that could be the case too Spirited, thus why I clarified as I did.
Jaune uses the Arc family symbol, which is a rainbow. That's what Vedran was saying; he was correcting the anon calling it a crescent moon. However, Jaune's personal symbol has never been confirmed, yes.