ZRH is in Switzerland, not Canada. Even if LX staff at ZRH are accomplished experts in Canadian law, you may rest assured that they could care less what Canadian law may be for a flight departing Switzerland for Italy.
Call centers do not make policy and the very fact that the "final say" is commended to the gate agent is your assurance that Canadian law is of no concern.
This isn't to say that you will be held strictly to the 8 kg. But, Canadian law won't have anything to do with it.