The short... Our GE refrigerator has a dual evaporator. Which means there is an evaporator in both the freezer and the refrigerator. So inadequate cooling in the refrigerator is most likely not related to the freezer at all like it is with models that do not have dual evaporators. After extensive research, diagnosing and testing I was able to determine that the refrigerator evaporator thermistor was not working properly. I replaced all four thermistors (two in the refrigerator and two in the freezer) and refrigerator is working fine.
The long...I began to notice condensation on the side by side refrigerator wall adjoining the freezer and food spoiling. The digital readout on the door was showing the refrigerator temperature in the mid to upper 40's. Most of the diagnosis and repair stuff I read or watched said that if the freezer is fine but the refrigerator is not that it is most likely a freezer problem. That it's not getting sufficient cold air into the refrigerator. Typically, either the defrost thermostat, the fans, thermistors or the control board are not working, and it could be any one of these or all of them. So I began to test things to try to test and diagnose the problem. I started in the freezer to no avail. After more research and testing I was able to diagnose the problem as the refrigerator evaporator temperature sensor / thermistor and most likely not related to the freezer at all. All of the research and testing took significant time and effort. You can search online and find videos that show how to test your thermistors at the circuit control board using a multimeter. Basically, you are checking the thermistor resistance at the circuit board plug. You can find a thermistor resistance chart online for your brand or possibly with the refrigerator tech sheet. For this GE model, at 32 degrees F thermistor resistance should be 16.3 ohms and at room temperature it should be around 6 ohms or a little less. If you get something different replace the thermistors. I recommend replacing all of them. When I say that the repair was easy, I mean the repair itself was easy. Finding the problem and getting to the repair was a bit difficult. Hopefully this makes your diagnosis and repair a little easier.