Sylvan is spoken by many fae natively, but many others choose to learn the language.
Abyssal, Infernal, and Celestial’s native speakers reside on other planes, but tieflings/aasimar respectively know them innately.
Same with Primordial and its descendant languages (Aquan, Auran, Terran, and Ignan; although Aquan took on more of a life of its own and is spoken by many more), and genasi.
Undersea Aquan is not spoken by many, but it's a subset of Aquan so it's under it.