OK, let's take a look at the ingredients:
If you can tolerate citrus you are golden! OK, so what if you cannot? The choice is up to you. The easy approach is to simply leave one ingredient out. In this dish, the lemon is just a slight change of emphasis in the sauce. If the cherries are pretty sour to begin with, this will likely turn out fine. However, you have some other options.
When I think sour, I know that citrus is out. So, what comes close that won't trigger a migraine? The obvious choices come first - white vinegar or white wine. A light hand is recommended - this flavor is like adding a subtle tint to a color. Another flavor that I really like that comes close to sour and often gets used with rosemary is ginger. Even when I have a full stomach, the thought of ginger and duck overcomes me with waves of desire. This is the way I will likely go. One other possibility is to try a sour fruit that is not citrus. The first idea that comes to my mind is Granny Smith apples, but you could go with sour grapes. Or you could go a bit sweeter with mangoes and back off of the honey, maybe completely. Just add a little of each at a time, starting with mango, and taste as you go. Many fruits can be on the sour side before they are fully ripe, so don't stop with these suggestions. Take this a make it your own!