The problem is to isolate the box enough. If you can heard the cat meow, then it counts as a "measurement" and the superposition disappears. If you can hear there is no heartbeat of the cat, then it counts as a "measurement" and the superposition disappears. If the cats move and the box wags, then it counts as a "measurement" and the superposition disappears...
So in practice the experiment only works with very small systems with a few atoms. Each year there are experiments with bigger systems, but they are usually frozen and very small. Perhaps one day we will be able to do the experiment with tardigrades.
So in practice the experiment only works with very small systems with a few atoms. Each year there are experiments with bigger systems, but they are usually frozen and very small. Perhaps one day we will be able to do the experiment with tardigrades.