Parsoid will magically convert an external link to another language wiki to the correct notation, e.g.

<a href="//fr.wikipedia.org/wiki/Foo>Bar</a> -> [[:fr:Foo|Bar]]

However existing wikitext users may not be aware of this and may try to type ":fr:Foo" into the link inspector. Currently this gets "fixed" to "Fr:Foo". Instead we should detect this special case and do something sensible.

Also before Parsoid does it magic, the external link will display in VE as an external link (with the external link icon) even though after save, it will become an interwiki link.