Currently it doesn’t seem to be done client-side, most of the issue is people can be using a war flag and disconnect at the end before results are submitted. This triggers the use of their flag and heroes - but since the disconnect occurred damage dealt isn’t saved.
It really wouldn’t work to link a viewer to another players device, so this type of request would require them to change not only their coding but the infrastructure of their servers… And probably require hardware upgrades on top of that.