Which speed level is this feat?

[Apex_Predator_GX]

A knight of the gods who was active during the Great War. It was said that she appeared with the thunder and left with the lightning, and that she was so fast that it was rumoured that she had already attacked her opponent when she spoke. However, she never attacked anything herself, and it was always at the time of divine punishment. Therefore, those who saw her would be reminded of their own past and their own past deeds

 

[Blahblah9755]

For the bold part: it’s obvious hyperbole, so completely unquantifiable. Something that starts with “it’s said that” is typically hyperbole, and almost always hearsay in verse.
Even if taken literally, it’s still completely unquantifiable, since there’s no indication of distance she traveled or distance to whatever lightning bolt is referenced, not to mention when lightning strikes you hear the thunder after seeing the lightning, so even if you could get a timeframe it would be negative.
The part that isn’t bolded seems like a poor translation, but if the intention is that she would say something, then attack an opponent before the sound reached them, then at least transonic. But it also appears to be hearsay, and is contradicted by the next line, so it probably wouldn’t be usable.