In Indonesia, most recent studies about teacher professional development have commonly focused on the programme's employment, effectiveness, problems, and the skills teachers gained due to the programme. Little focus has been placed on the consistent investigations of how multilingual interventions take place in feedback-giving practices, notably in teacher professional development training. Through a case study, we sought to establish a sociocultural framework for examining what instructors learn from the uncertified teachers' exchanges in delivering spoken feedback and how this influences instructors' approach to multilingual interventions. All language use during encounters, reflections, and interview responses were recorded. Uncertified instructors valued bilingual feedback for meaning-making interactions, which improved their comprehension and provided a model for multilingual interventions in feedback-giving practices. The research sheds new light on how instructional practitioners and teachers can effectively offer feedback for highly valuable interactions and knowledge.