There are a lot of different traditional ways to start an Easter fire. In England in Anglo-Saxon days, it was customary at the cathedrals to start the Easter fire with “crystal” – ie, with sunlight through rock crystals, the same way you could start a fire with sunlight through a magnifying glass. St. Boniface wrote Pope Zachary about it at one point, and was surprised to find out that it wasn’t the custom in Rome.
Obviously, they’ve been starting the Easter fire in Jerusalem for a long time in a similar way to what is reported today, because we have references going back to the 3rd or 4th century. That was long before the Great Schism, so it has nothing to do with Catholic vs. Orthodox.
If it’s an annual miracle for Jerusalem’s church, then yay, God! It speaks to the holiness of the Church of the Holy Sepulchre.
If it’s a local wonder of nature, then yay, God! The created world is very beautiful.
But if it’s something that does have a natural explanation, keeping it secret is not necessarily fraudulent. Back when YMCA Indian Guides and Indian Princesses was a thing, there used to be a big annual firelighting ceremony in the fall. After some nondenominational prayers, there was a “secret” method of lighting the bonfire, which the dads knew about and which was kept secret from the daughters. (Although I was pretty sure I knew what the secret method was.) They weren’t seriously trying to pretend that they had firelighting powers, or that the Great Spirit was sending down fire direct from Heaven. It was a showy backup for some nice prayers, and a bit of fun display.
Shrug. Never going to be a patriarch of Jerusalem, so it’s not my problem.