During a February hearing, Judge Richard Leon, the judge assigned to the Africa Sting cases, reportedly said he had "zero sense that there was an omnibus grand conspiracy" alleged in the 16 separate indictments charging 22 individuals with, among other things, conspiracy to violate the FCPA and substantive FCPA violations (see here). Judge Leon also reportedly told the DOJ that "what you think is so transparent is not" and he urged the DOJ to "take a step back" given that the DOJ may be so "close to trees that it can't see the forest." (see here).
The DOJ presumably took a step back, went back to the grand jury, and the grand jury returned a superseding indictment (see here) charging, among other things, all 22 individual defendants in one big conspiracy to violate the FCPA.
The superseding indictment, unlike the previously filed superseding indictment against Daniel Alvirez (see here), does not add much in terms of substance, although it does contain greater detail regarding certain e-mails, meetings, and telephone calls relevant to the conduct at issue compared to the original indictments. Further, this allegation in the superseding indictment was not apparent from the original indictments - "the defendants would agree that the products they would supply in connection with Phase One [of the deal] would be consolidated for shipment to Country A."
Judge Leon previously indicated that he would not try 22 individuals together in one case. In response, the DOJ has proposed a "reasonable division" of the defendants into four groups. (See here and here for more).
Also, Christopher Matthews of Main Justice, who attended today's court hearing, is reporting (here) that another defendant, Jonathan Spiller, is in plea agreement talks with the DOJ and is likely to plead guilty. Matthews reports that neither Spiller, nor his counsel, were present at today's hearing.