El Sueno and the rest of the cartel don't claim credit for the embassy bombing. Because they didn't do it. They don't try and refute the fact they did it, though, because despite El Sueno's claims Villains Never Lie won't fly. Also, they DID murder a DEA agent by torturing him to death.Their situation is screwed no matter what.
Kataris 26 is apparently named after Tupac Katari, the legendary revolutionary. It could also be named after Pac Katari himself. It's why he changed his name so there was an easier association. This is part of his Fake Ultimate Hero and Miles Gloriosus tendencies.
Karen Bowman reacts with extreme disgust to La Gringa despite the fact she's an Antivillain and a Fallen Hero who was assisting the rebels as well as coarced into working for El Sueno. This makes sense with the fact La Gringa is an American and also a educated woman with some resemblance to Karen herself. Karen views La Gringa as a Category Traitor.
Why did UNIDAD continue to stalk the Ghosts despite the latter making a treaty with General Baro? Because the Ghosts have killed members of their organization, are in the country illegally, assisting a revolutionary government, and wrecking all sorts of havoc. Even the honest members of the group are likely to think of the Ghosts as terrorists.
There's also a number of UNIDAD officers directly in the service of the cartel like El Commandante.
Captured Antivillain characters in the Santa Blanca cartel are likely to get far less forgiving deals than El Sueno due to the fact they know significantly less than him. Also, they're being reparated to the United States, which is far less forgiving of drug offenses than most nations.
The Ghosts systematically dismantle Santa Blanca's cartel but in the process kill hundreds of Bolivian citizens, wreck the economy, arm a Dirty Communists guerilla insurgency, and leave a massive power vacuum. Especially since so much of the previous economy was destroyed and the government co-opted by corruption. Fallen Ghosts confirms this and shows the country has been made even worse.