I tamed a cat and then got a piece of Lead. I changed the Lead's name to "Leash" using an anvil and when I hooked the lead to my cat and took it off, the lead's name was changed back to "Lead". I also tested this on my wolf. The same thing happend. The other tiny little bug I found with the lead is that when you hook a lead to an entity, the lead is on the entity's hitbox instead of texture. This makes the lead appear above the entity. I'll show you the bugs in the video.