I'm not sure if this is easily doable, just an idea: when you go to a Wiktionary page which does not exist, list all existing pages with the same title on other Wiktionaries.

Most of the time I don't use the search function and just append the word to the url. If it's a French word and it's not in en.wikt I'll change the url from "en." to "fr." It would be great if I didn't have to guess and could just see the available pages. Maybe this could be implemented on the Wikis directly with T163734?