The Reborn Princess's Magical Revolution ~The Executed Villainess Rebuilds the Perishing Noble Family~

Yarinaoshi Koujo no Madou Kakumei: Shokei Sareta Akuyaku Reijou wa Horobiru Kadon wo Tatae Naosu
やり直し公女の魔導革命~処刑された悪役令嬢は滅びる家門を立てなおす~

Adaptation

novel

Falsely accused of attempting to assassinate her fiancé, the Crown Prince, Countess Leticia and her entire family were executed. She was then reborn in Japan, retaining the memories of her past ambition to become a mage-engineer, and achieved success as an engineer — but then she died in a traffic accident. And now… she's been sent back to her 12-year-old self, *before* the engagement!? There's no way she'll repeat the same mistakes. An engagement? Absolutely not! She'll use her skills to develop new magical artifacts to uncover the conspiracy and save her family! (Source: Hifumishobo, translated)