I also have a 15v4, and had the exact same issue that you do (or did).
I loosened the four screws holding the track pad click bar in place to the point where the bar has the smallest amount of wiggle/play to it. I left the top screws (under the battery) tightened as they were upon arrival. I tightened all of the casing screws consistently. This resolved the issue completely for me. Short version is that the click bar screws were too tight.