I have a theory

I think Pandora is a not bad guy hear me out

Shaula was a red herring linking back to Flugel

Pandora needed to make sure Elior forest froze or else Emilia wouldn’t end up with roswaal / become a royal selection candidate

So my bet is on Pandora being somehow connected to Subaru similar to any witch but she might have more to say then shaula offered or echidna

Echidna is final boss since it’s echidna