Yours system uses a single cable to send the keyboard & trackpad signals to the logic board. What can happen is the battery swells pressing on it. I would first recommend checking your batteries health using [https://www.coconut-flavour.com/coconutbattery/|CoconutBattery] paste a screenshot of the apps window here for us to review [guide|21499] depending on what this shows you’ll likely need a new battery. [guide|4502]
Another source of problems is the trackpad its self as its the junction point for the cables. a liquid spill can mess up the trackpad or if the liquid gets to the back side mess up both. At this point you’ll need a new trackpad and you may want to replace the cable as well. [guide|7587]