Expression For Linking Camera Keyframes Cross-comp

Hey there,

Thanks to all the help here I've been able to continue automating a good portion of a project that I'm working on, but I've run into another issue.

I have the following composition:

It contains a camera layer that has 3 keyframes. I want the third keyframe to occur 150 frames after the end point of a layer in a different composition called "Audio 1". Here's that other composition I'm refrencing:

To accomplish this, I tried using the following expression:

var externalComp = comp("Text With Transition and Sound");
var t = externalComp.layer("Audio 1").outPoint + 150*externalComp.frameDuration;
valueAtTime(time - (t - key(3).time))

While this does set the end of the keyframe to the proper point in time, it  also changes the behavior of the first two keyframe which I don't want as the first two keyframes have my text fly in from in front of the camera like so:

In the above correct version, while it's hard to tell, the first 19 frames are the text flying in from being completely non-visible to completely visible.

With the expression however, the first frames look like this:

The letters start off as already awkwardly visible. Then, they stay there (unmoving) for the first 16 frames. Afterwhich, they'll teleport to where they're suppose to otherwise be at that point in time. I've tried adjusting the Z axis of the first keyframe to be a greater or lesser value to no avail.

Does there exist an expression that'll accomplish moving the placement of the third keyframe of the camera based on the endpoint of "Audio 1" that wont effect the other keyframes?

Thank you as always.