How did Charlemagne's reforms encourage the use of written Romance languages?

Charlemagne’s reforms did not directly aim to promote vernacular languages; rather, they inadvertently encouraged the development of written Romance languages by reestablishing high standards for classical Latin.12

By inviting scholars like Alcuin to his court to revive "pure" Latin, Charlemagne created a sharp contrast between the standardized, scholarly Latin used in administration and the evolving speech of the common people. This linguistic gap made it increasingly obvious that the vernacular and Latin were distinct entities.12

The practical impact of this realization was solidified in 813, when the Council of Tours decreed that sermons should be delivered in rusticam Romanam linguam ("the rustic Roman language") to ensure they were intelligible to the congregation. This shift marked a pivotal moment where the need for comprehensible communication necessitated the use of the vernacular in religious and, eventually, legal contexts. Consequently, the Carolingian effort to standardize Latin served as both a cause and a catalyst for the emergence of conventional written forms for the various Romance languages.231