The regional courses for science teachers in Southeast Asia (SEA) offer participants with the inservice knowledge and skills while promoting deliberate discussions about recent issues related to teaching profession and the sharing of best practices in science education. A total of 21 teachers from eight SEA countries were purposefully selected to participate in this course as nominated by their respective education ministerial officers. Given that the participants came from different countries and attended the course virtually for four weeks, this article aims to chart participants’ insights to be backed as data for future course facilitation. The findings are based on post-course evaluation garnered from 21 unstructured essays provided by participants with a focus on two key aspects: (1) the challenges that participants encountered prior to or during the courses, and (2) a recommendation for a similar course in future. Five challenges emerged from the findings include; English proficiency, socio-cultural preferences in social activities, digital technology access and skills, time and schedule constraints, and institutional challenges. In terms of recommendations, participants shared their thoughts on how to better facilitate and manage course administration. Since the majority of professional development courses are held at the national level, this study helped to consolidate country differences and served as the foundation of evidence for future courses that will adapt similar region-based online participations.