Interpreting practice in Tunisia, be it consecutive or simultaneous, has witnessed a significant transformation over the past decade given the rising need for such a business in multilingual communication. To this end, interpreter training programs have become widespread. However, little research has been conducted to explore and trace how scaffolding unfolds among trainees or novice interpreters. Against this backdrop, the present study, being longitudinal and multimodal in nature, seeks to probe into the development of simultaneous interpreting (SI) competence among students of translation and interpreting within a Tunisian interpreter-training program spanning over seven years as from 2018 to 2025. Using a diverse, rich corpus comprising written translation, sight translation (ST), consecutive interpreting (CI), audiovisual translation (AVT), and simultaneous interpreting (SI), and informed by contrastive discourse analysis, this study investigates how linguistic, cognitive, and pragmatic micro-skills evolve across modalities to ultimately shape SI proficiency. Results suggested that SI does not emerge as a standalone skill but rather develops cumulatively through the progressive automatization of micro-operations, including segmentation, syntactic reformulation, inferential reasoning, lexical retrieval, and pragmatic alignment. The latter were first cultivated in translation and subsequently reinforced in ST and CI. AVT was found to contribute to learners’ SI readiness by enhancing semantic condensation and multimodal attentional control. The study highlighted the need for curricula that preserve translation as a foundational component, strengthen ST and CI integration, and incorporate AVT as a cognitive enhancer. The study case offers broader insights for interpreter education in multilingual contexts, demonstrating how a structured, multimodal progression supports both cognitive resilience and professional readiness.