This study compares three tandem-learning models implemented in Korean language education at Ruhr-University Bochum between 2020 and 2026 in collaboration with partner universities in Korea, the United States, and Germany. It explores how different communication environments shape learner participation, intercultural interaction, and language learning experiences. The three models comprised a Native–non-native Digital Tandem, an L2–L2 Virtual Collaboration, and an Analogue Penpal Tandem, each representing a distinct approach to tandem pedagogy. Drawing on classroom observations, questionnaire responses, interviews, reflection journals, collaborative learning products, and oral reports, the findings suggest that each tandem model supports different yet complementary dimensions of learner engagement and language use. While the Native–non-native Tandem promoted authentic communication and intercultural exchange, the L2–L2 Virtual Collaboration enhanced learner confidence and collaborative knowledge construction, and the Analogue Penpal Tandem encouraged reflective writing and deeper interpersonal engagement. Rather than identifying a single optimal model of tandem learning, the findings suggest that different tandem formats serve complementary pedagogical purposes and should be selected according to specific learning objectives and learner needs. The study therefore positions tandem learning as a flexible pedagogical framework that can be adapted to diverse educational contexts in contemporary Korean language education.