Yes, they can be used, but to be clear, we're talking about preserved cherries using the canning method, NOT any type of canned cherries bought at the grocery store. Since canned cherries are preserved in a sweet liquid, you can use the liquid as the water in the recipe. You can omit the sugar entirely if the canning liquid is sweet enough or just use a small amount to suit your taste. The simmer time will also need to be reduced by a few minutes.