It appears like certain regular expressions in the FileImporter wikitext cleanup code are not Unicode-safe. For example, the link [[兵庫県立考古博物館]] doesn't get the interwiki prefix. It should become [[:ja:兵庫県立考古博物館]], but doesn't.
Example: https://commons.wikimedia.org/wiki/Special:Diff/435420995
Reported here: https://www.mediawiki.org/wiki/Topic:Vqwxi9chttpgxdy7