I know that, and Titanica isn't really coming back. But that doesn't mean anyone IC knows that, and Fran saw first hand the destructive powers of lady Godzilla. Fran intends to take advantage of the threat in order to draw attention and stir a bit of confusion (Because at this moment Fran is mostly fighting for herself and not openly cooperating with Endian and Friends).

Unless you're saying that Fran can't use her illusion powers to even summon a fake version of Titanica who can't even do any real damage. Fran is an illusionist after all, not a reality warper. I just try not to tell you when I'm using illusions or not because misdirection and feints don't work nearly as well when you know they're misdirections and feints.