@Cloutaku
no, I have to disagree. She is definitely not talking about herself being a "bad girl".
She said - [じゃあ さっき]
[くちをつつしみなさい っていわれても むししたのは]
[わるいこ ですね ボズラ—さん]
Which literally translated as [Then, just before]
[when being told to close your mouth and disregarded it]
[so it means that you are a "bad child", mr. Bozler]
Last sentence doesn't have pronoun, so i can understand the reason behind that mistake. But there is no way anyone would think that she is talking about herself in that kind of context. Basically, she just catch up him redhanded on his double-standard thinking, aka "you are a bad kid, if you don't listen to your elders", so she pointed out that he doesn't have a right to talk that way, when he isn't any better.
And just from situation, why would he feel shame after her slandering herself being a "bad girl"? She just dragged him down to her level calling him a rebellious kid, so he is ashamed of it.
Also, she doesn't refer to bandit subjugation as "mistake". It doesn't make any sense. Her wording might have been indeed better (since, for example, translation-apis really want to translate it as mess/crap/etc), but in that context it can only be read as "deed" or "credit". She is asking him if he have any achievement, like herself. Then she sarcastically said that she doesn't see that bandit subjugation as something special and all of the people sitting here for sure did it once or twice as well. He couldn't say anything, because he doesn't have even that kind of "lowly achievement", so he backpedaled from it, and just picked on her age instead.
Mage discussion doesn't make sense in your translation exactly because of those inconsistencies. If you are not paying attention, it's not a rare situation when entire meaning of the phrase become opposite of the original.