The Hall Sensor of the VAC9010H “bidirectional voltage and current meter” is shown on the positive battery cable with the arrow mark pointing towards the positive battery terminal in the diagrams, which I assume is the direction of a charging current in the charging mode, i.e increasing battery charge. If the Hall Sensor was positioned on the negative cable of the battery I presume the sensor would have to be positioned with the arrow pointing away from the negative terminal?
You can put negative cable into sensor, but actually it is not necessary to do that. As long as the current direction changes, sensor can check it at once.