Before translation: Hero must have said something about Mimic's disguise which accidently insult her mimicky, pissing her off.

She's miffed because the adventurer can pick out other disguised threats easily but can't pick her out, as if she posed 0 threat to him

What are the chances of her being the transformed princess from a while ago who ended up forgetting who she originally was? I mean, he is not reacting to her for a reason.

At this point she comes off as just being salty he isn't giving her enough attention.