The YunoHost forum needs to be integrated with auto translate. It should show all forum members all forums in their native tongue. Something like auto translate would really bring thw forum together.
most of the time, automatic translation are quite bad, I think we should let people use the language they want/can write without hiding it.
I do not feel comfortable with something that may hide this usage. Native content is also important to help local language community to exits (and to answer in the same language).
Let’s go for a quote:
If you talk to a man in a language he understands, that goes to his head. If you talk to him in his language, that goes to his heart.
Nelson Mandela
but, you may have forgotten the link that describes your proposal, maybe it is something really different!