Yikes! I don't know the answer but will be praying for you that they will be fine. I know that wilted cherry leaves are toxic and can be deadly, but not sure about the pits. Hopefully someone will come along here soon to answer, but maybe a call to a large animal vet in the meantime?
Cherries are iffy, because the leaves contain cyanide, a deadly poison. I would think the pits had cyanide but am not sure. Cherry leaves were part of the problem that killed foals, caused mares to abort down at the Thorobred farms in Kentucky a few years ago.
I KNOW peach pits have cyanide, are poison to people.
Perhaps calves weighing more than people, can take eating the cherry pits without being harmed as easily. Hope it is a one-time deal for them!