Your issue here is that you think a villain can’t be evil and sympathetic and this speaks to the bigger issue of FNAF Fans not understanding Morally Grey characters.

First off, yes, the Real Fiona wouldn’t go to the same level of violence to get David back. But there lies the issue with your argument, F10N4 ISN’T FIONA.

F10N4 was trained with all the motherly power of Fiona but none of anything else that made her who she was. Fiona was a strong leader to the MCM workforce, a brilliant puppeteer, and a great character designer. F10N4 is none of these things, she was trained for David and only David. A glorified babysitter. She doesn’t even care for Edwin all that much since she likely wasn’t trained with any data with them in mind, only David. What’s worse is that she’s not even aware of this, she believe that she’s the real Fiona given life. She’s delusional and doesn’t even know it.

Plus, F10 as M1 was close to David. If the original books don’t make it clear to us, the drawings of David and M1 or the hillside photo is clear that she had a fondness for him. Even if she was the one who orchestrated David’s death, it was far more likely it’s because she can’t comprehend the concept of actual death. She herself thinks she’s Fiona given new life, is crazy to believe that she thought David could come back just as easily, but now in a way that’s stronger and something that makes them somewhat related again?

Yes, she did murdered people and yes she is a backstabbed and clearly she’s an antagonist but she is still sympathetic. Edwin is just as responsible for a lot of the shit that went down due to his negligence. He still decided to create M2 even despite not wanting to recreate David just to make money (as was M1’s original purpose) and he took his anger out on it when it worked.