Plone.app.multilingual : how to populate translated fields with original content?

I successfully use cs.linguacopier as a helper tool to create folders and pages in other languages (to later be translated). It's works well, but I was asked to add this feature directly in plone.app.multilingual... I'm aware than I could use its Google translation feature, but I don't want to use Google services (and provide my credit card even for a free trial).

So how to fill all the fields of the target language(s) in a babel view with the content from the original language?

Plone Foundation Code of Conduct