Hey, During Wikimania, Shani told me the famous "Not in the other language" tool [1] doesn't work for Wiktionary (because the tool is based on Wikidata but Wiktionary uses something called Cognate). On my way to the airport, I wrote a hacky small thing to make things easier for Wiktionary users that you can find in [2]. Here's an example, list of French nouns that exist in German Wiktionary but not in English [3]. The code can be found in [4] and needs lots of love if anyone is interested.
HTH
[1]: https://tools.wmflabs.org/not-in-the-other-language/ [2]: https://tools.wmflabs.org/dexbot/tools/nitolw [3]: https://tools.wmflabs.org/dexbot/tools/nitolw/index.php?fromLang=de&toLa... [4]:https://github.com/Ladsgroup/NITOLW
Best