I have difficulty understanding your problem. Do you mean that the form labels and text need to be translated? Or the validation error messages? Or what?
Are you sure you have properly included jQuery itself as well as jQuery-validation plugin?
Hi, thank you for your reply. It is simple issue but it seems technical issue at MailChimp.
Usually we have folders like fr, uk or longer en-gb.
If this is detected it should automatic translate but if I understand MailChimp uses just autocomplete and I can not detect language and detect via API.