If the writers of the show used Egyptian hieroglyphs intentionally, there must be an explanation within the story as to why they appear. I can't and won't profess any knowledge of ancient Egypt or its culture, so please excuse me if my theory misses key historical realities. The Island was inhabited by a society or civilization in ancient times. They built the Temple, the Ruins, the Four-toed statue, the Frozen wheel, and likely a great deal more. On many if not all of these remnants, we see hieroglyphs.