Back to basics. If the umpire hears it clearly, its called. If the umpire doesn't hear it, then it is considered not touched.
Leaving it up to grainy footage is a failure waiting to happen.
They need to completely scrap the ARC or goal review system and start again. Make it basic. They have a snicko for when it hits the post. Thats it. Everything else is umpires call. Put it back on them, its their job, I wonder how many are afraid of making the wrong call because the review might spot the smallest thing.