https://www.thecollector.com/britain-dark-age-kings/
Maybe of passing interest...
Yes interesting to see what is slowly coming out
The Biblical expression, at least in translation into modern European languages, normally uses an abstract noun rather than an adjective, so if this is what's going on one might have expected "sons of liberalitas" rather than "sons of liberalis".
Is it possible that confusion ran the other way, "Nudd son of Generous" being misremembered as "Nudd the Generous"? I can't help reflect that if Dark Age Welsh treated patronymica the same way as Renaissance Swedes did, Nudus Liberalis would be ambiguous between "Nudd the Generous" and "Nudd son of Liberalis".