Hi! The invoice is always generated in the language of the site at the time of generation. This means that if you switch your backend (or whole site) to English, it will create English invoices, and if it’s Dutch, it will create Dutch invoices. If you want to do this independently from the site/user profile language, you need a more advanced solution like WPML or Polylang in combination with our Professional extension, because unfortunately this is quite complex to do.
That’s a relatively costly and high impact solution though, if most of your customers are English and your site is also in English (I assume), I would recommend to set your backend to English too, which would be the most simple solution.
Hope that helps!
