my only thought is that I would go easy on the chocolate mint... it's really strong, at least the stuff I grow is. It would probably be easier to use peppermint, which is milder, if you have it. Then you could test it and graduate to the chocolate mint (a kind of spearmint) next time. If all you have is the chocolate mint, then I would suggest maybe scaling things way down and making like 1 cup of cherry mint "sauce" first to test the amounts... like put a splash of water in a pan, and add a little sugar, cherries and some fresh mint. Cook a while until the cherries give up their juices. Taste along the way. Remove the mint when the flavor is strong enough. Then you can thicken that small amount of sauce with a little corn starch and put it on icecream or whatever, and then scale up the amounts for making jam. A least... that would be what I would do... but I'm just thinking this up on the fly.