The Sacrificial Second Princess's Perplexity ~ Shipped off as a Hostage, Warmly Welcomed as a Sagacious Savior ~

Ikenie Daini Koujo no Konwaku: Hitojichi no Himegimi, Tekikoku de Chi no Saien to shite Daikangei o Ukeru
生贄第二皇女の困惑 ~人質の姫君、敵国で知の才媛として大歓迎を受ける~

Source

The puzzle of the sacrificial second princess: The hostage princess receives a warm welcome as a talented person in the enemy country
Ikenie Daini Koujo no Konwaku: Tekikoku ni Hitojichi to shite Totsuidara Fushigi to Daikangei Sareteimasu· 生贄第二皇女の困惑 敵国に人質として嫁いだら不思議と大歓迎されています
novel

Claire was treated as a failed princess because she didn't follow the education of a proper lady. She was sent on an arranged marriage with an enemy kingdom, expecting to lose her life at any moment. Instead, she was welcomed with open arms and unexpectedly made the fiance of the crown prince. In fact, she had been eagerly awaited as a "living fount of knowledge." She had been treated as a useless person in her homeland, but now she could embark on domestic reforms and started making paper to help her new home. However, some people did not take kindly to this...... Claire tried stop her own poisoning and get out of the situation, but... (Source: Earthstar Luna, translated)