no, area is fuelmass, b4005 is time.
if the pcm tells the injectors to dump let's say 2.5ms of fuel, it will get less than that, because the injector at first doesnt flow at all, and then it flows less then the official 'static' flow rate. short pulse adder is the amount of time that's needed to make up for that by artificially telling the injectors to open longer than they would have to open for if they provided a perfectly linear flowrate.
ok, here's a pic, it should be easier to visualize. area under the red curve is going to be bigger than the blue curve. thus we must make the red curve longer to effectively make up for what the blue is missing.