I have found with my code that the beforeChange function is only working when the user interacts with the cell, if a cell is being passed data from another sheet, the values of the cell will update but the beforeChange will not fire and as such does not automatically update my chart. If I interact with the cells beforeChange works and my Line Chart updates.
This is a snippet from my overall project, the cell that is being prepopulated in the final version is to be read only, with a more complex formula and displayed in a separate container within the page which is why it is setup the way it is
my JS fiddle example is below, any advice is greatly appreciated.