Previous research on the L1 acquisition of motion event expression suggests that mapping multiple semantic components onto syntactic units is associated with greater difficulties in verb-framed than in satellite-framed languages, because the former require more complex structures (using subordination). This study investigated the impact of this language-specific difference in English--French bilingual children's caused motion expressions. 2L1 children (n = 96) between 4 and 10 years and monolingual English and French children (n = 96) described video animations portraying caused motion events involving multiple semantic components. Results revealed reduced rates of subordinate constructions in bilinguals' French descriptions, and more so in older than younger children, while English responses aligned with monolinguals. Semantic density of responses strongly predicted syntactic complexity, but exclusively in French. These asymmetric findings indicate a task-specific syntactic relief strategy and are discussed in the context of theoretical claims about universal biases of event encoding and bilingual-specific optimisation strategies.