This expression usually works with other layers, (as shown with the link to my music page above) so i'm not sure why it's not working with this one.
Looks does not expose its internals as separate property streams that can be addressed with expressions. Your approach is simply unsuitable. You need to use other plug-ins or keyframe by hand based on your Soundkeys output as reference.
Expressions always generate numbers. If you reveal a property in the time line and timeline and there are no values associated with the property then you cannot use an expression for example in this shape layer Rectangle Path 1>Size, Stroke Color, Stroke Width and Fill Color have values. Colors are an array of 4 numbers with a typical range of 0 to 1 and red with 50% opacity would look like this: [1, 0, 0, .5] . Some color properties, like Fill in a shape layer, do not respond to values in the alpha channel but the array still needs to contain 4 values.
Looks>Look and Curves>Curves do not have values. You can only use expressions on properties that have values.
So, from my understanding, it's not possible to add an expression to the layer I want. The only way to still have chromatic aberration would be to add the effect to a "transparent" solid? If so, i'm not sure how to make that effect only my logo- and not my entire composition. Also, @Mylenium previously stated that I would have to individually key-frame every part where I want the effect to take place. Is this true? Or will that solid idea work if I tie it with sound keys?
If you want to add an aimated LOOKS or even curves property to a composition add an adjustment layer, then add Looks to the adjustment layer, then use sound keys to drive opacity of the adjustment layer. The other option is to animate the Strength of Looks:
You just have to apply your expression to a property that has a numeric value.
Thank you very much!