The script has its own scope and the app has its own scope. The script cannot use variables and methods outside of his scope.
What you could do is create a callback from the app where you call the script. Something along the lines of:
function updateEditField_cb ()
updateCOEs;
end
also, make sure that the edit field you are trying to edit supports the data type you are trying to write, for example a numeric edit field cannot accept a string (in this case 'hi') as field. hence it will show nothing
