"they're not tied to any specific plate" means the order of the texts is always the same no matter which order you get the plates. For example, the first text is always "When the universe was created, its shards became this Plate." If you get the draco plate first, then the draco plate will say "When the universe was created, its shards became this Plate." If you get the insect plate first, then the insect plate will say "When the universe was created, its shards became this Plate."