Feder Grotesk was registered with the Kartei des Vereins der Schriftgießereien on 15 May 1911, over a hundred years ago. Any copyright protection it may have enjoyed has long since expired.

Oh, so does this also mean that anyone can release such a revival under the original name?

does this also mean that anyone can release such a revival under the original name?

Not necessarily: typefaces names, often, are trademarks and can be registered for copyright protection. In the present instance, the fact that Elsner and Flake claim trademark on the name EF Feder Fraktur should give you pause to use Erbar's original name for the typeface...