We have very general descriptions for now, though I am referring more to who the Brokers are overall rather than the specific mechanical identity.
Copy-pasting myself:
Quote:
- The Obscura (WUB, mechanical themes are card draw and control): Conmen, grifters, spies. Oracles use their knowledge and prophecies to control the city and maintain balance between the families while they line their pockets.
- The Maestros (UBR, mechanical themes are sacrifice and removal): Artists who see murder as their medium. They're more old money and refined in dress.
- The Riveteers (BRG, mechanical themes are aggro and big beaters, good at buffing each other up): Union workers, mess with them and they will take apart the infrastructure below you.
- The Cabaretti (RGW, mechanical themes are creature synergies and go wide): Party throwers, the most inclusive and accepting, have a lot of politicians in their pocket.
- The Brokers (GWU, mechanical themes are protection and control): Doomsday lawyers who will keep you safe but at what cost? Always there when something goes wrong, whether you want them to be or not. Protection rackets and a lot of favor trading.
So we don't know whether/how the charms fit the factions overall at this time, though the Cabaretti Charm very obviously fits the go-wide theme (which is also apparent in the faction leader's card). It's more that the Brokers Charm doesn't show "law firm that shows up everywhere to offer people protection and fixes in return for favors" much at all.