The stream id is only used between a Akka Projection gRPC producer and consumer to identify which of the entities the producer serves that a specific consumer wants to consume, without tying that to the service-internal entity type name.
Not sure what you mean with “en event producer has not been called”. Note that Akka Projection gRPC is not a push but a pull based way to consume events, nothing will happen unless a consumer connects to the producer and requests it to stream events.