Apply lang to localized name:* values #6834

In an element page’s “Tags” section, the table cell for the value of each localized name, such as name:fr=* or alt_name:en=*, should have a lang attribute set to the language code. This would help the browser choose an appropriate font. Screen readers would also be less likely to trip over text in languages that are related to the user’s preferred language.

For example, the Yellow Sea node has name:ja, name:ko, name:zh, name:zh-Hans, and name:zh-Hant all set to the same value, but the characters should look significantly different based on a language-appropriate font being applied. As I understand it, the visual differences are about as significant as presenting “Londres” as the English name for London. We probably don’t want to get into the business of choosing specific fonts, but even just telling the browser which language it’s in will help the browser choose the right font.

I don’t know of a comprehensive list of localizable keys. In principle, any freeform text key can have localized subkeys, but the most common one by far is name:*=*. Other common keys include addr:street/city/place:*=*, brand:*=*, operator=*, and species=*. Ideally, the code would check each subkey to see if it’s a valid IETF language tag, but I don’t think Rails comes with anything like that. As a workaround, a regular expression like the one mentioned in pnorman/spirit#80 (comment) would detect these language subkeys reasonably well.