I did running takeoffs on water on a what I assume were Bell approved floats on a regular basis doing the long ferry flights required, as did the other pilots with the dozen or so helicopters we had on floats in my company.
I had one complete and sudden engine failure in a Bell 47 on floats. I don't recall any "difference" in autorotative entry or flight either on that day or during the training I did. On arrival at the ground [not water]I got the landing right knowing that a run on meant probably rolling the machine over. In my opinion any competent helicopter pilot would have no trouble mastering the minor differences that floats make to the handling characteristics of any helicopter approved for floats.
These slight variations were treated as common sense airmanship in the country I was operating and were included in the company training. Perhaps in your domocile, 4Dogs, the government does not credit you with either enough intelligence to see the differences or ability to handle them. All I can say is that in Canada, where extensive float operations have been carried out since the early fifties, no one was required to pass a government endorsement requirement for floats and personally I don't recall any incidents where lack of any such requirement caused problems.
Your suggestion that these things can't or shouldn't be done just shows your insularity. If you are indeed flying floats, I would suggest you get in contact with people in other parts of the world and broaden your horizons. You might learn something.