@Keegan suggested I come here. [[ https://meta.wikimedia.org/wiki/User:Alexis_Jazz | My user page ]] causes me to have a list of languages I don't understand on Wikidata and the caption feature. I didn't even know my user page doubled as a configuration/preferences page!
Please ignore level 0 languages.
Update 18 January: a better solution would actually be to configure the languages you see in https://meta.wikimedia.org/wiki/Special:Preferences. Levels and babel boxes wouldn't matter anymore. It would also make more sense, because no user can be expected to guess //this// is how you configure which languages you can edit.
Update 20 January: ignore the title. This request is **not** Commons-specific. Whatever solution we come to, it should apply equally to Commons captions and Wikidata labels.