A masterful Film Noir, not for the faint of heart.

Watched it a couple of days ago, enjoyed it a lot. As you said it's a struggle trying to understand what is going on, specially since you always miss some things when you don't understand the spoken language.

SPOILERS
I was watching it with others and at the scene where Silien was trying to convince the girl that she "heard" the shots someone in the group was hella confused so I told him my prediction that Silien was going for two things simultaneously, getting the girl free from her past and by her edited confession the police would be forced to let Maurice walk and thus Sillien would be able to kill him and revenge Salignari's death. Turned out I was right.

Of course I don't think there was any clue to predict that inside his cell Maurice would order a hit and the way that whole thing would turn out. It's a typical thing though that so great plans in films in the end almost always fail to something small or random. Specifically in a dark movie like this and with the main guy (Silien) having performed so many "bad" actions (killing Maurice's girl) I expected him to die in the end one way or another).

Not a masterpiece, Silien fate, as it is, feels completely out of character
A twist that betrays the entire psychology of the character and the film

Melville direction was great as always, but that alone isn't enough to call it "masterful"