www.wysiwygwebbuilder.com

If I am not mistaken WWB 16 offers a tool for translation of headers etc. I wonder where can it be found?

Do you mean this?
https://wysiwygwebbuilder.com/language_text.html

I read in whatsnew

- New feature: Added the ability to customize/translate the text of the various items (headers, buttons)

but it is for CMS i now found out