In Titanian lore, "gremlins" are mischievous spirit creatures that are responsible for the failure of machines. According to Titanian beliefs, gremlins live in greater numbers in areas of magic -- such as Bosch -- but they can only jump so high, so there are not as many of them that can reach the sky islands, such as Rephidim ... which explains why machines work better there. Basically, gremlins are just an anthropomorphization of the phenomenon of quantum uncertainty.