If a reference is made to an non-written article in a Wikipedia in e.g. Danish, then the link [[alpha]] will show up in read, indicating that the article is a non-written article in Danish, but there is no easy way to get to articles in other languages that may already been written.
The reference could then be made using [[:en:alpha]], but this will leave a number of references hard coded to the English article on the subject, even if the article is later written in Danish, so that approach is not to prefer.
So it would be an advantage if there was some way to indicate that an article was not yet written in the current language, but the article is available in other languages, so the reader may follow the reference it it is OK to read the article in another language.
Other readers/editors seems to miss a feature like this too, since they start doing language specific references using non-standard "(sv)", "(fr)" in an article like https://en.wikipedia.org/wiki/Eiger .