>>23352562
There's no explicitly stated Mafty remnant group. But Rue Rahvata rose up shortly after Mafty's Rebellion, have a similar modus operandi and their example MS incorporates a bunch of Messer parts so there's an implication that they're at least linked somehow. However Rue Rahvata was also noted to operated in the colonies so even if there's a direct connection they're unlikely to be straight up just Mafty remnants.
I don't think they've been mentioned in Cluster yet, but given the current themes and topics I wouldn't be surprised.