I know that the vast majority of Webflow customers here are probably from English speaking countrieswith English speaking clients. However, those working in countries with other native languages should add up to a good number too.
I'd love to see the CMS interface translated into different languages. I certainly would be more comfortable to sell Webflow sites to clients whom I know are not that confident in English.
I would also be happy to help with translating into German, and I'm sure others would be happy to help with their languages.