Hey ajanani ,
I am not sure of the exact output of the converted YoloV2 model, but I would say that on-device decoding is not supported for YoloV2. You would have to instead use NeuralNetwork node to get the detections, decode them on host, and pass them back to SpatialLocationCalculator.
However, I'd strongly suggest you to use either YoloV3/V4-tiny or YoloV5 model, for which we provide tutorials here and have on-device decoding, instead of older YoloV2.