If it is a historical property, the cemetery could add to the "history" of the property.
Any easement on a property could be a negative for resale... It all depends on the buyers. Somewhere out there, are buyers that will buy the parcel thinking that the easment and visitors are just fine. These buyers may just take a little longer to find the property than those that say: " Oh no, I can't deal with that..."
Best of luck.