The author could not have changed them.

On the contrary he modified his instrumentation greatly, simplified and perfected it.
We know that the authors, in utter defiance of mythology, wanted a happy ending and so brought Eurydice back to life a second time.

Love accomplished this miracle and the work ended with the song "Love Triumphs," which is exceedingly joyful and in harmony with the situation.

They did not want this ending, which was in _Orfeo_ and which Gluck retained in _Orphee_, at the old Theatre-Lyrique and the Opera-Comique, and they replaced it with a chorus by Echo and Narcissus.
This chorus is charming, but that does not excuse it.

Joy was what the author wanted and this does not give joy at all.