Steps to reproduce:

1. Add a link
2. In the search field, enter an interlanguage link, e.g. "sv:Apa"
3. Click Done

Actual result:
Link shouldn't be shown. I think this is the case, though I wasn't aware of interlanguage links before I stumbled on this.

Expected result:
Link shown as "sv:Apa" (and leads to the article "Apa" on SVWP), but when the page is saved no link is shown.

Additional information:
Tested in Firefox 66.0.2