@Kaleb, you are correct, I verified the calculation and the JWs forgot about the leap year. The other calculations are also correct, the Jewish calendar is not lunar or solar, it is lunisolar. I don’t know how the JWs got to their calculations, but they are off for no reason I can find.
The Metonic cycle was in use during the Second Temple (invented by the Greeks a few hundred years BC) is still in use today by both the Jews and Buddhist, Islam uses a lunar calendar and because in Islam any writings are infallible, it no longer keeps track of the solar system.
The problem if they are going to use a strict lunar system as they claim by astronomical observation of the number of months (although the equinox is related to the sun) and not use leap years, the memorial will have to shift slowly over 33 years and coinciding with the Jewish calendar will happen once every 33 years. However this is not how they calculate, they use a solar calendar with astronomical observation of the lunar cycle, basically, had the ancients done this, they’d be inserting random leap days every year. It would be extremely difficult to calculate anything anywhere in the future without a modern computer, as the earth’s solar equinox drifting wouldn’t be established for over a thousand years. You can’t just decree a new calculation every so often.