@SquigglesJP I'll cross out errors and put in the correct replacements. Additions (missing letters/words) will be in italics. In order:
"Even I had to
sacrificed sacrifice my child."
"It's been taught to us by our
family families for generations" ("Family" could be correct (and it is grammatically correct) but I believe he's talking about all three pillars of the empire here, so "families" should be the correct word.)
"However, I think
it would have been better if we firmly rejected them back then."
"I'm sure the other lords didn't like sacrificing their daughters
too either."
"I'm sure it wasn't only my house that
experience experienced that."
"Sorry to trouble you all the time, Meruurina" (The comma was missing)
"At the very least, you are aware of it huh" (You could add a question mark at the end, add a comma after "it", remove "the very" and remove the comma after "least" and it would be grammatically correct. Removing the "huh" at the end so it's no longer phrased like a question would be good as well. If you want to keep "the very", at least implement the comma changes. Which way you go with it depends on the original meaning so I can't say which option is best.)
"Strange... Right now, I'm not that scared of his red eyes that much. Actually, it's quite pretty..." (This is a mess. Firstly, using "that" twice in one sentence that way is a mistake; it's saying the same thing at the start and end of the sentence. Either remove "Right now," and the first "that" or remove "that much." I recommend removing "that much", as I think the "right now" works better to convey how she's thinking in the moment. Secondly, "Actually, it's quite pretty..." is confusing in terms of what it refers to. I assume it's referring to his gaze, but she didn't say his gaze wasn't scary to her, she said his red eyes weren't scary to her. The easiest (and IMO best) way to fix this without changing the structure of the previous sentence even more than you already have to would be to just change it to "Actually, his (optional: put "red" here as well) gaze is quite pretty..." Your other option is to change it to "Actually, (they're/his eyes are/the red is) quite pretty...")
"The people who can kill Maou is someone who is blood related or the person who is rank 2nd
And the one that killed Maou will be the next Maou
Right
... ?" (Another mess. In this case there are also several options for rephrasing but I think the meaning is clear enough that I can just suggest one restructuring to replace this with. If what I suggest isn't close enough to the original meaning, feel free to ask me for the other rephrasing options. My first suggestion: "The only people who can kill Maou are someone who is blood related or the person ranked 2nd...
And the one that kills Maou will be the next Maou,
Right?")
"It's a little different. They only have the right to challenge Maou
Those who have the right to do it must follow the rules" (This one is messy in a way that just requires rephrasing. My suggestion would be "It's a little different from how you think. They only have the right to challenge Maou
And those who have that right must follow the rules.")
"This is your chance, you know?" (The comma was missing.)
"I want to know your answer." (I think adding a period at the end adds a sense of gravity; he's giving her an ultimatum, after all: "Me or them?")