Sorry, I was a bit tired last night. Qrow mentioned something about an infiltrator not being just a pawn, but the one responsible for Autumn's, who I presume to be Amber, condition. I'm thinking Cinder used to work for Ironwood and was able to acquire information about Amber through him. That's why he was surprised when Qrow said "your infiltrator". I may be reading too much into this, but hope this helps!