Language ability by itself does not establish special or advanced knowledge for L-1B. The case must explain relevant knowledge of the organisation’s interests or processes and show that the U.S. role involves that knowledge.
Find the underlying business capability
Foreign operating experience may be relevant when it has significant value to the U.S. operation, but describe actual work and learning rather than assumptions based on nationality. Explain how language is used within a qualifying assignment, if applicable.
Corporate relationships and the continuous qualifying year abroad remain separate requirements. Language ability alone does not meet the standard, and framing a case around it tends to weaken whatever else is there. Look for the business capability underneath.
In most genuine cases the language is how a real capability is delivered rather than the capability itself: the employee understands the company's products, its technical standards, its regulatory position or its customer arrangements in a particular market, and communicates that understanding in the relevant language. Identify that substance and describe it, then mention the language as a fact about how the work is performed. Remember also that the other requirements are untouched by this question: a qualifying corporate relationship must exist, and the employee generally must have completed a continuous year of qualifying employment abroad within the preceding three years.