Steps to replicate the issue (include links if applicable):
Thanks to Chinese Wikipedia user Sohryu Asuka Langley Not Shikinami for identifying this issue.

• Add language conversion tags containing links to a page, for example: -{zh-cn:[[维基百科]];zh-tw:[[維基百科]];}-
• Open the revision using the Visual Editor. See the relevant revisions on Chinese Wikipedia: Revision 85133380 or direct link to the edit interface.

What happens?:
The links rendered within the language conversion rule box are ./维基百科 and ./維基百科, while normal links beside them render correctly as https://zh.wikipedia.org/wiki/維基百科.

What should have happened instead?:
The links rendered within the language conversion rule box should also point to the correct URLs: https://zh.wikipedia.org/wiki/维基百科 and https://zh.wikipedia.org/wiki/維基百科.