Yes, the green patina* is a corrosion product that could undermine the silver plating.
Possible solutions for the exposed areas: Brush plating of silver, brush plating of tin, application of plastisol (brush-on vinyl in a solvent), application of grease or wax (I prefer Alcoa’s Electrical Joint Compound (EJC) No. 2), or painting.
*the green patina is not an oxide; it consists of malachite (basic copper carbonate, CuCO3Cu(OH)2) and usually lesser amounts of brochantite (basic copper sulfate, CuSO43Cu(OH)2) and atacamite (basic copper chloride CuCl23Cu(OH)2).
The copper oxides are the red cuprite, Cu2O, and the black tenorite, CuO.