I'm not aware of any.
Yes, the crossings are on private land. They are used only by producers who own the land or their employees, who cross them to work in the fields or woodlots on the other side.
In the 1800s, the lands were probably forested and were not being used. There were a lot fewer problems at the time, but since then, the land has been cultivated and now the grade crossings are only used by producers to access their fields on the other side.
I have not heard of any issues related to accidents or incidents involving landowners or anyone else.