There are two things that you can take a look at to debug CEL.
If you go to the module in adminstration app you can see on the right all outputs that are generated by your module. That way you can verify your statements. Keep in mind that it only shows something if the statement outputs something. If you don't see anything loosen the "where" conditions or split your statement into multiple statements
If there is an error happening in one of your statements or expressions (in the case of a real Java error) there will be an alarm created. They are visible in the normal alarm list but you will also be notified on the home page of administration if there was an error.
There are two things that you can take a look at to debug CEL.