I´m not sure about but so many times I hear that the complex making capacity of the cyanide is the big advantage of this complex. Then, the baths are more stable and easy to be controlled, and the plating rate increases. Even for Zn plating nowdays there are some alternatives without CN, the plating tith some other metals (Cu, Ag, Au, i.e.) are still operating with CN baths. Some companies reject the non CN technologies (mainly with Zn at the beginin) because that kind of bathes requeire a strict control of operative conditions (temp., pH, concentrations, and so on) that the CN process.
Nowdays this is an industrial researching topic. I don´t know about technologies with AgNo3 but if exist, is possible that the formula of the plating solution is not public. That´s very common in this kind of industries. You may try to ask some plating solutions suppliers to check if there is some other alternative without CN.