We all know that Nero can't use magic, but she can speak. She could have easily told the story to Asta and the others about what happened. She could have easily told the truth to the current Wizard King, who could have easily found out everything, or maybe even turn back the first Wizard King and Nero to human form.
Why didn't Nero tell the Black Bulls (or anyone) about the devil, elves, Licht, and the first Wizard King?
Nero was not able to speak before the elves re-incarnated.
Edit: Actually it wasnt until the shadow palace was summoned at Clover Castle. This is from the Wiki
> When Asta asks if she is Nero, she confirms and explains that she was originally human and could not speak as a bird until the Shadow Palace was summoned
please add some source or explenation.– KjenosMay 26, 2020 at 13:13
@Kjenos Have updated it with Source May 26, 2020 at 14:42