This study examines CLI as a dynamic component of L3 development rather than a deficiency. It addresses three research questions: (1) whether language-awareness-based instruction influences early L3 vocabulary development; (2) how it affects the nature of CLI in production; and (3) what qualitative changes occur in learning behavior. The study involved a six-month intervention with Chinese university students who have firmly established L2 English knowledge and are beginner L3 German learners. The EG received explicit instruction in L3 strategies, while the CG followed a moretraditional, L2-oriented instructional approach. Quantitative data from pre- and post-tests were analyzed using descriptive statistics and independent samples t-tests in SPSS. Qualitative content analysis was applied to learner associative paths to identify lexical organization patterns. The results indicate that learners in the EG tended to demonstrate greater lexical expansion, particularly in tasks requiring active vocabulary retrieval and associative processing. Meanwhile, these learners produced a higher number of cross-linguistic interference errors in the early phases of learning. Rather than indicating regression, these errors functioned as transitional phenomena associated with hypothesis testing and strategic engagement with the target language. Over time, both the frequency and nature of interference changed, suggesting increasing selectivity in the use of cross-linguistic resources. From a pedagogical perspective, the findings challenge strictly norm-oriented approaches to error treatment. Instead, they highlight the potential value of instructional practices that encourage learners to reflect on cross-linguistic relationships and to actively manage their multilingual resources, thereby supporting more sustainable learning processes in German instruction after English.