The solution is quite obvious: let the user specifying his own language, use it in a tag, and let the user optionally filter/download only the selected content.
Local bubbles can be a problem in the long term but are important for welcoming new users, especially if they are not able to speak a foreign language.
Knowing that this option is standard, would make people more inclined to freely switch language when posting, truly enriching the linguistic and cultural presence in the network, and so promoting Nostro locally.
Instead now most use only English, this proves something is not working right.