The prevalence of Autism Spectrum Disorders (ASD) has resulted in research on treatment efficacy, lending itself to quantitative analyses. In contrast, ethnographic studies have offered the benefits of analyzing lived experiences and exploring the uniqueness of ASD individuals. Using the Linguistic Ethnography (LE) perspective, this case study investigates the connection between multilingual practices, behavior management, and behavior-logging app usage. It looks at one cross-cultural family (Indonesian-Belgian) with two children diagnosed with autism. Multimodal data were collected for ten weeks virtually and five weeks in the family’s home in Belgium. The data collection focused on the family's multilingual and behavior management practices and specifically on mobile app usage to document the behaviors of the non-verbal son. Analytical frameworks were drawn from Multimodal Ethnography (Dicks et al., 2006) and Multimodal Discourse Analysis (Kress, 2011a). The findings indicated that linguistic and cultural diversity, both internally and externally, caused a layer of complexity in attending to a non-verbal child. The case study showed positive outcomes of multilingualism. However, it highlighted the struggle of building consistent communication between family members and health professionals, which affected the effort to find a successful treatment plan. The behavior logging app helped parents identify parts of the son’s behaviors and reflect on their behavior management strategies. However, it also underscored the real-life challenges of documentation. In this case, mobile technology may be more useful when supported by health professionals. Although the case study notes family successes, it calls attention to the extraordinary realities of cross-cultural ASD families that need more representation through ethnographic research.