It's more verbose, and the semantics are slightly different, but to capture this pattern you could have one radio selector for "primary language" and then check

It's more verbose, and the semantics are slightly different, but to capture this pattern you could have one radio selector for "primary language" and then checkboxes for "additional languages". Often I see this as a dropdown for language, with a "+" below it for "add additional language" that then exposes a second dropdown for another language and so on. I don't think we have any real-life controls that we interact with that have this behavior so it's not easy to see a clear affordance.