Honestly, we'll probably have to wait for the official. Since Baal's like her Archon name, yeah? Like how Morax was Zhongli's. Raiden Shogun should be an equivalent of Rex Lapis as well. Besides, we might meet her incognito in the future too.
Let's leave her name as Raiden first, as that is consistent with the other archons we already have, her name is probably supposed to be a refernce to honkai impact's raiden mei so we should go with that. We can change it if future events make it more appropriate to call her Baal, but currently we dont know much about her.
@Erogedragoone stop reverting people's edits. If you don't like how a character is named bring it up in the forums (topic #18797), don't keep changing it back after multiple people have changed it.