Fallback to cs
I make this proposal after a discussion with Mormegil and Dvorapa: can we set Czech as fallback of Slovak and vice versa? If we do this, when a translation is missing in Slovak but available in Czech, the translation in Czech will be shown to Slovak users instead of the English original (and vice versa for Czech).
According to Lindsay, there are formal intelligibility studies that found written Czech and Slovak to be 98 % intelligible in both directions. The source might be Nabelkova, M. 2007. Closely related languages in contact: Czech, Slovak, "Czechoslovak". International Journal of the Sociology of Language 183: 53-73.
On the other hand, according to Eurostat and CLDR, English is known by less than 30 % of the population in CZ and SK.
It is really good idea, in fact every Slovak understands Czech language on very high level. I (as native Slovak) can only agree.
- Yes, it's possible. We have for instance a reciprocal fallback between pt and pt-br.
- Coverage is ok for the most frequent extensions, but not for all of them. Maybe this change is going to affect/help mostly non-Wikimedia users. Is English less surprising/annoying, for the average user? (I'm not aware of data other than language proficiency statistics, to answer this question; maybe we can think of something else too?)
Special:LanguageStats/cs vs. Special:LanguageStats/sk can give an idea: MediaWiki extensions are respectively 54 % and 27 % translated, so we have at least 27 % messages in sk which would use the fallback. I'll try to make a list to see how much overlap there is.
Thanks, but it seems not to match reality in a few random tests I used. E.g. Notification-add-comment-yours2 is listed in sk and not cs, while it exists in both (and is an outdated/unused message anyway). Dtto Centralauth-editgroup-subtitle or tpt-desc. OK, User-profile-preferences-emails is in sk but not in cs, but it is unused anyway. Dtto ga-threshold. Whoa! Finally I have found Security-restricttogroup which seems to be a correct example. But the overall validity seems to be not very good by this random test.
Anyway; as I have said, I am not against the idea, just that I do not consider it that much important or useful. If someone does, by all means, go ahead.
While it can make a sense to set it in generic MediaWiki installation (although sk as a fallback to cs is quite unusual(*) - I can't recall any software (except for that where sk is the original development language) doing that, everywhere there is a fallback to en or any other worldwide language), it must obtain a consensus on both sides on relevant Wikimedia wikis.
Also mind phabricator:T13267.
(*) besides fallback from language with higher number of speakers to language with lower number of speakers is quite illogical
Wikimedia wikis don't automatically rule MediaWiki i18n; there are hundreds of MediaWiki wikis in Czech and i18n is there to benefit as many users as possible.
There's nothing illogical about a reciprocal fallback, see also the referenced research; the "bigger" language, as defined by number of translation, will simply use the fallback less. Per the list provided above, cs messages falling back to sk are 7 times less than sk to cs. You can probably translate them all in an afternon. :)