109 fits under "more than 100". 109-40=69. The numbers are consistent as described. They turn out to be inaccurate because he didn't actually gain over 100 before the drop, based on the interview that draith linked, but they are at least internally consistent, so it's entirely possible that the error was in knowing the middle weight, not in math. Either way, the error isn't nearly as extreme as your original claim made it out to be.

It says he gained weight between the two movies, and dropped weight after gaining weight; that doesn't provide any information as to when the dropping happened relative to the films, although I agree that the ambiguity in the way it's phrased is potentially misleading and a bad choice of words.

In short, the English is technically accurate, though potentially misleading, and the math error might be a relatively small factual error or a relatively small math error, not a whopping huge mistake. But if it makes you feel better, you're right - the guy who made it is an idiot, so am I, and you really are the smartest person on the internet.