Christopher, may I suggest you use an expression instead of keyframes?
It’s way faster to modify.
fadeDur = 1.5;
ease(time,inPoint,inPoint+fadeDur,0,100)
fadeDur is the time you want the effect to animate, the default with keyframes is two seconds, on the expression is a second and a half.
The last value (100) is how much you want the range selector offset to go in your text object, i.e. if you only want half of the sentence, set it to 50, etc.
Best,
D.