Examining the use of multimodal translingual practices of language learners is a promising area for the study of semiotic resources in online multimodal language learning. As such, although L1 use is theoretically established as one of the many semiotic resources to be drawn upon for meaning-making as part of learners' integrated repertoire, its role as a catalyst for the establishment of social presence is under-theorised. This paper presents detailed micro-analyses of the videoconferencing interactions of three pairs of language learners, and offers a social semiotic account illustrating transformative processes of transformation, transduction and mimesis (Bezemer & Kress, 2016). This study makes a unique contribution by demonstrating how translingual practice is mobilised with concomitant multimodal resources, and how this social-semiotic practice interweaves with all three dimensions of social presence (affective, interactive, and cohesive). It proposes that as a contributing factor to social presence, L1 use can assume a more prominent role in support for online language learning and teaching by helping learners project themselves socially and emotionally into their online interactions, and engage in a variety of transformative processes offering various learning potentials.