I'd argue that this is not as useful in Wiktionary as it is in Wikipedia. No one has explained why this feature should be adopted in Wiktionaries. Wiktionary is just a dictionary and we search by the title. Now the implementation of this feature is happening tomorrow 28th November and no one has explained how the feature helps (is of use) in Wiktionaries.
Topic on Help talk:Extension:AdvancedSearch
No one has given feedback in 12 months on why it wouldn't be useful..
Translated: Communities have responsibilities as well....
Hi Hartz, thank you for your feedback. It is possible that this feature will be less useful in Wiktionary than in Wikipedia, but we still think that it will be useful to some Wiktionary users. You can still do everything you did with the old search interface with the new one and if you dislike the new interface you will be able to disable it in your user settings. If you think that Wiktionaries would need different search options, we’d be interested to hear your suggestions. We did not yet got much feedback from Wiktionaries.
The new Extension:AdvancedSearch interface did find for me existing string in '''no''' way. I knew, that that string really exists, because I '''did''' write it. Please, return the older system, which wasn't lying about existence/nonexistence of concrete string.
If some improvement for Wictionaries, so create better ability to find special letters (with unusual diacritics) as e.g. ệ OR ử OR ů; or for korean ability e. g. find part ㅈ in sylable 존 or in whole word 존재.
Hello Kusurija, we did not change anything on the functionality of the search but only reworked the search interface. The development of the search engine is done by the discovery team at the Wikimedia Foundation. If a search that previously worked now does not work anymore you might want to report this to them.