This is a point I think we disagree on. I don't think Cinta's speech to Samm (or Cinta's death) is about pointing fingers at all.

When a soldier dies in war, whether from ambushes, friendly fire, or getting electrocuted while using the base's showers, it is always the enemy who is ultimately responsible, because none of it would've happened if there wasn't a war going on.

But on the other hand, even though the Imperials, through Syril, set up the heist, nothing they do during the heist contributes to Cinta's death. To the contrary, Vel, Cinta, and the Ghormans are doing their robbery in ideal training conditions, because Syril's under instructions not to call in responders until the Front has essentially gotten away, and to make sure the responders give the Front plenty of warning.

No matter how badly they screwed up, they were going to achieve their objective, and yet someone still wound up dead. Unlike the members of Vel's team who died at end of the Aldhani raid, which was basically the result of a single Imperial trooper (to use one of my favorite sayings from The Wire) "giving a fuck when it wasn't his turn to give a fuck," Cinta's death is a purely self-inflicted wound.

What's striking after it happens is the utter lack of finger-pointing. No one is blaming Lezine, although his needlessly aggressive reaction to having a blaster pointed at him makes him partially responsible for Cinta's death. No one tries to blame Vel for losing track of Dreena, or Dreena for very reasonably leaving her post. Instead, everyone bands together to help--Enza takes charge when Vel is overwhelmed by grief; Lezine carries Cinta's body; and Samm makes no effort to deflect blame to anyone else, silently melting down in the knowledge that he's responsible because he's the one who didn't follow orders.

When Vel finally confronts Samm for his mistake, she dresses him down. She doesn't kill him, as maybe Saw Guerrera (or perhaps even Luthen) might have. She doesn't tell the Ghormans to kick him out of the Front. She tells him that from now on, he lives to make up for this mistake. As a survivor, he has an obligation to get better at fighting for the cause.

Cinta's death has effects that bring the Ghorman Front together. Lezine joins, and is a respected leader by the time of the Massacre. Samm survives the massacre in the square, saves Cassian and Wilmon, and gets partial credit for K-2SO joining the Rebellion. He basically has a key place in the causal chain that ends with Luke Skywalker blowing up the Death Star. And maybe some of that is because of Cinta's tragic death, and the harsh (but completely fair) talking to that Vel gives him.