The event times reported in the results file correspond to when the relevant events occurred. For the Key element, it stands for when the relevant key was pressed, and for the Canvas element, it stands for when the print command was executed. So the difference you calculate corresponds to how many milliseconds passed between when the print command of the Canvas element was executed (which should be almost exactly when its content started being visible on the page, barring performance issues) and when the keypress was detected (which should be almost instantaneous, again barring performance issues). That difference includes the time it took for all the commands between the printing of the Canvas element and the keypress to be executed (basically,just newKey and log, so maybe 1ms) but that shouldn’t matter because all you care about is how long it actually took for the participant to press a key after seeing the Canvas element, regardless of whether the script executed commands during that time
Jeremy