There is also a Thread by the incredible Leolaia, from years ago, which in addition to Jeffro's perhaps ? shows that EVERY year they get it wrong ! Their method of calculating is wrong of course, but Leolaia showed from the historical roots of Passover why it is wrong every year IIRC.
But as above, they really do not care, it gives them a feeling of superiority that they know better than the Jewish Scholars !
Many years ago when I first left, I had read Leo's Thread, and spoke about what I knew to an elderly JW lady, a former F.T. Pioneer and full on J.W, who surprised me by saying, as she walked away " I don't CARE if it is on the wrong day !", I think that attitude would be general now among J.W's.