No, No, No...
The Big 11:00 number for Helen is simply called...
"Water"...
And in true musical theatre and theatrical fashion, it's the only time we actually hear Helen speak, the inner Helen. Saying all the things she's been wanting to say... Singing them. All the "handicaps" disappear for a few minutes. And then we, the audience, realize, that we also have a handicap - the "handicap of speech".
Hmmm...
Of course, the final song of the show would be a duet between her and Annie Sullivan. A wordless duet - just Annie and Helen signing. With a shadow-play of the climactic "water scene" playing on the white scrim upstage.
Hmmm....
Actually, that could be quite moving if done right.