- For example, if I'm on Wikiquote, do I want to also see relevant search results from Wikivoyage, Wikipedia or Wikinews?
- Or, if I'm on Wikipedia, just show me results from other projects?
Topic on Talk:Cross-wiki Search Result Improvements
Do we want these new search results to work across all Wikimedia projects?
I wonder if specific projects have a given relevance for other projects, like Wikitionary have a higher relevance for Wikipedia, and a lower for Wikispecies. It will probably also change given the categorization of pages within the projects. Wikispecies has a high relevance for articles in Wikipedia within biography, but would have a low relevance for art.
If you do a search in a project, then the categories could be used as an indicator for how relevant (likely) some other project would be, given this specific result set. If a project is highly relevant, then the number of hits could be increased from 1 to 3 (just an example, use whatever number).
It really depends on the nature of the question. If someone is looking for the meaning of the Latin word ''vicesimanus'', Wiktionary information will be of most use, and it may not matter which language Wiktionary the results come from, as the word may only appear in a few projects, and might be illustrated with a picture, with a list of translations into other languages, or at least with an explanation in another language besides Latin. Likewise if someone is looking up the pronunciation of a word, or its syllabification for the purposes of hyphenating it, or synonyms. All of these features of a word may be presented on any Wiktionary, and may be found independently of the project language.
I don’t think the average user searching English Wiktionary would be happy with a definition of a Latin term that was in Finnish, Russian, or Chinese—generally in any non-Indo-European language or any language that doesn't use the Latin alphabet. The lack of readable cognates makes those pages useless. Look at the Russian page for gato (Spanish "cat"). If you don't at least know some Cyrillic, you can't get much out of that page. Finnish gato is actually better than I expected, but only because there are some cognates (Espanja, Portugali, and substantiivi). You can translate those pages using your browser or online tools, but I think that's getting into the realm of “power users” unfortunately.
My intuition is that what most people want is results in the language of the project they are on, or projects in the same language. (Exception: when their query is clearly in another language. Exception to the exception: when they are on Wiktionary—which is where I often go for words I don’t know even when they are not in English.) Users could also use results in other languages they can read (which they need to specify or we need to surmise, say, based on browser settings). Only power users and researchers are going to dig into results for languages they don't know. This may change over time as machine translation gets better and people become more sophisticated about handling text in other languages—but I think most people aren't there yet.
I’m open to other opinions on user preferences and the typicality of any given use cases, of course!
However, there may be some technical limitations. We can’t index English Wiktionary both with all the other English projects and with all the other Wiktionary projects. Searching across all Wiktionaries without a shared index is probably too resource intensive to be practical.
Re: "Only power users and researchers are going to dig into results for languages they don't know." I disagree. During the time I was seriously active on Wiktionary, requests for translations into languages the user did not know were very common. We had daily requests for assistance.
Interesting! Requests for translations into, say, Russian, seems very different from using a Wiktionary page in Russian (without machine translation).