Most “multilingual” chatbots translate their interface. The visitor still asks a question in Dutch and gets an answer in English, or an answer built from your English pages. That is the half nobody advertises.
Three separate problems
- The interface. Buttons, placeholders, the privacy notice. Easy — it is a translation file.
- The reply language. The model can answer in any language; it needs to be told to follow the visitor rather than the site.
- The content it reads. The hard one. A Dutch question should be answered from your Dutch pages, not from the English originals a translation plugin also stored.
The retrieval problem nobody mentions
Search is language-sensitive in a way people underestimate. A question written in an alphabet your content does not use — Bengali, Arabic, Greek — matches nothing: not the vectors, not the keywords. The assistant then says it does not know, about a fact that is sitting in its index.
The fix is to translate the question into the content’s language for the search step only, and still reply in the visitor’s language. It costs one tiny extra call, and it turns a confident “I do not know” into a correct answer.
With WPML or Polylang
- Index content with its language recorded, so a Dutch page answers Dutch questions.
- Run one full sync after installing the translation plugin, so existing entries get their language stamp.
- Remember that your own wording — the welcome message, button labels — is separate from your content, and needs translating in the tool you already use.
Answer quality across languages
One detail worth checking: a model translating its own English phrasing word for word sounds wrong to a native speaker. A Dutch visitor told “Ik ben sorry” gets the same impression as an English visitor told “I am regret”. The instruction has to ask for native phrasing, not translation.
Questions
Do I need a translation plugin?
Not for the assistant to answer in the visitor’s language — that works on any site. WPML or Polylang matter only if your content itself is translated.
Can I force one language?
Yes, and on a single-market site you often should. Mixed-language answers on a site that only serves one country look like a bug.