After suite a bit of exploration in the secret pathway to the templar, i found 2 shady spots i believe might be chest spawn locations. One of thèse spots can even be seen through the normal way. Right before getting to the templar on the right side of the pathway there is a ledge in the shadows and bars there préventif you from getting to the other side. But you can acces behind. those bars by the secret entrance. Is there something to It? Time and trial will tell