Seems like a good time to bring this up.
I haven't reread episode 5 in awhile. But for some reason I was always under the impression that Meta Erika didn't exist until she was brought up to their level in the Witch Trial scene. I don't really remember her interacting with Battler, Bern and Lambda at all until that part.
and this part of episode 5 is probably what got that in my head.