This study examines selected results of a year-long pilot training program aimed at enhancing plurilingual education practices among teachers through a participatory action-research approach. The program involved 13 experienced teachers and addressed challenges in integrating plurilingual approaches into practice. Initial data from the full group of teachers highlighted positive attitudes toward plurilingualism but also revealed concerns about linguistic diversity as a barrier to effective teaching and classroom cohesion. The study focuses on three teachers, tracking their experiences with co-designing educational activities, implementing them in the classroom, and evaluating the outcomes. The results show that, while localized, a shift in their perspectives occurred. Each teacher developed and implemented their own teaching intervention, overcoming perceived difficulties, which led to increased confidence and a growing sense of agency in integrating Pluralistic approaches to their teaching practices. This shift was facilitated by a co-design approach, promoting collaboration between teachers and researchers. The intervention was gradually embedded into everyday practices, empowering teachers to adapt changes to their contexts. Ultimately, teachers were able to bridge the gap between theoretical perspectives on and practical classroom implementation, developing their own “sense of plausibility” about the pedagogical actions proposed, which became incorporated into their pedagogical framework and teaching vision.