Presumably the variation in devices would be observed across all the fonts and therefore average out. I.e. there is no reason why people who got font A would d

Presumably the variation in devices would be observed across all the fonts and therefore average out. I.e. there is no reason why people who got font A would disproportionately be using device X. You make a good point about the possibility that people did not actually see the passage in the intended font.