Yes they are. The elders are the managers of the KH, and if a crime happens at the KH and the police are called, they will want to speak to them. There are many situations that call for someone at the KH to be in charge and who else is going to be but the BOE? The WTS should back them up legally and not leave them to hang out to dry. However, I bet they will.
Not everything that could occur at the KH is within the realm of something the elders could reasonably expect to anticipate-- but a lot is. This is why the shepherds should know the appearance of their flock. . This calls for real work by the elders to know those who attend and anticpate problems. They want special respect, they have to earn it.
There have been fights, medical emergencies and shootings at the KH and other churches too. The elders are not bouncers or cops but sometimes they may have to remove disorderly person(s) or get involved and call an ambulance.
As to the field service, any elder after the Conti case who allows a child or teen to work with anyone but their parents is just up to the job of elder.