I grew up speaking spanish as well, and remember the Coke bottles and other labels thusly marked. Marca registrada is indeed spanish but I'm not at all sure S and W meant it to be. Maybe they intended Latin, or figured it's close enough to latin, spanish and portuguese to work for all three. In any case I'm betting they didn't hire any linguists before they decided to include it.
I like me some tacos de lengua, y de pierna tambien. De ojos, not so much.