Kyuutei Majutsushi no Konyakusha: Shoko ni Komotteitara, Kuni Ichiban no Tensai ni Misomeraremashite!?

Melanie, a member of the prestigious Stewart family, is an "underachiever" with little magic power. When her engagement is called off for that reason, she finds herself in the library, where she succeeds in deciphering an ancient lost language! Nevertheless, when her uncle invites her to a magic school, Quinn, the best court magician in the country, discovers her hidden talent...!?

(Source: Kadokawa, translated)