Need Help with Multilingual Retrieval in Vertex AI Agent Builder

Hi,

I'm building a multilingual chatbot using Creating Data Store, Discovery Engine, and Reasoning Engine.

Right now, I have one data store that contains both English and German documents. The problem is: when I ask something in English, it doesn't retrieve relevant content from the German documents — even if the answer is there.

I'm looking for a solution where the retriever can search across both languages.
For example: if the query is in English, it should also check German documents and return the right response if available.

Any suggestions or best practices would be really helpful!

No repository file, test, or code entry point is identified; the report requests guidance on multilingual retrieval across a shared data store in Vertex AI Agent Builder. First establish whether a concrete SDK change or reproducible test is expected, since the issue provides no completion criteria.

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