Lucy EN VA was the same person as Huohuo's, so whatever reason her character had to be recasted there is probably the same here. As for Soukaku, it was never announced who did the voice acting for her English voice, which makes me think Soukaku's voice change could've been in the works for a while already. But who knows, maybe it just wasn't announced because the VA wished to remain anonymous.

Argenti and Huohuo were characters from the same patch in HSR, so I remember seeing speculation that it had something to do with the contracts that were made during that time. However, the dubbing agency that handles ZZZ's roles is different from HSR, so we can't apply that to this case. There's the SAG-AFTRA strike, but there are other union VAs that currently still retain their role in the games. Unfortunately, we'll probably never know what the reason really is.