In the Customer Agent’s Identity settings, there’s a Language dropdown where you can select specific languages the agent should respond in. HubSpot’s own wording is: “If no languages are selected, the agent will respond in the language it detects from the customer’s first message.” In other words, auto-detect isn’t restricted to a published fixed list — it’s designed to pick up whatever language the customer writes in and reply in kind, rather than being capped at a set number of languages.
If you do want to lock the agent to specific languages (rather than relying on auto-detect), the dropdown draws from HubSpot’s standard supported product languages: English, Spanish, French, German, Italian, Dutch, Polish, Swedish, Finnish, Danish, Norwegian (Bokmål), Portuguese (Brazil), Chinese (Simplified), Chinese (Traditional), Japanese, Korean, and Thai — 17 languages total, per HubSpot’s general language offerings page.