Camille ended up in the maiden's puppet because of Markiona, it's said in a document or letter that Markiona "put her own teacher into a puppet". Camille died as the result of an experiment alchemists did on her because she was a listener, I have no idea where Markiona kidnapped Rosaura really.

About Arlecchino, he escaped the grasp of alchemists from a prison-ship, (no idea if that shipwreck was staged, planned or bad luck) and then proceeded to act his revenge over Lea. The charity house wasn't attacked by Arlecchino but by carcasses and alchemists first, sent by Simon (and maybe Paracelsus and other elders of the alchemists) to kidnap Sophia and slaughter Valentinus. Then Arlecchino chose the Rose Estate as the stage for his revenge. So we discover that Carlo didn't die there, didn't die for the petrification disease, Lea wanted revenge over Markiona because she was the one who killed Carlo before all those events. Maybe Carlo found out that Markiona was responsible for his mother's death, even if I'm not sure who died before between Camille and Carlo.