Using expression to apply and offset tracking data to clone stamp gives error?

I have applied tracking data to the positions of both clone brush stroke and clone source and then used an expression to offset the tracking data and return the stroke and clone source point to the original position in order to remove an object from the composition.

First attempt (including a line break):

thisComp.layer("

tracker").transform.position-[3027-1615.5, 1509-1663.5]

Result: "Error: Unterminated String Constant"

Second attempt (deleted line break):

thisComp.layer("tracker").transform.position-[3027-1615.5, 1509-1663.5]

Result: "Error: Layer named "tracker" is missing or does not exist" (but it definitely does, and is named properly)

I tried a semi-colon ";" at the end of the line. No luck.

Third attempt:

deltaX = 3027 - 1615.5;

deltaY = 1509 - 1663.5;

x = thisComp.layer("tracker").transform.position[0];

y = thisComp.layer("tracker").transform.position[1];

[x-deltaX, y-deltaY];

Result: "Error: Layer named "tracker" is missing or does not exist"

Why is it telling me the layer doesn't exit when it does? Is this a bug or am I doing something incorrectly? I am using AE CC 2017. Is there a way to fix the error, or do I need to find a new method to use the clone stamp with tracking data?