Currently, there is, as far as I am aware, still no solution to the fact that, for example, some languages use a regular colon as a letter, but the software renders this in links as an interwiki link (for example, a link to [[cu:wĭ]] at links to http://cu.wikipedia.org/). Some people suggested using the triangular colon, but this isn't correct. Eventually, the answer was given to me that this could not be considered a bug because none of the languages that require this are "major", and thus there is no need for a solution...
I would submit that to the bug tracker again because that is a major bug and maybe something for the usability project to aim for.