Translating a plugin did nothing, and nobody could see why
@lvarnava translated several plugins, updated, and found his work missing. Reasonably, he asked what he'd done wrong. Nothing, as it turns out.
Weblate merges a plugin translation into that plugin's langs/ directory. It has no reason to touch the plugin's index.php, so the version the plugin declares stays exactly where it was. The release then builds the package, translation and all, and publishes it under that same unchanged version. Your install compares what it has against what is offered, sees the same number, and concludes there is nothing to do.
So the translation shipped. It sat in the package on the server, correct and complete, with no route to a single user. Neither end was wrong about anything, which is why it went unnoticed for two months.
Plugins now get a build number that moves whenever their contents move, so a merged translation shows up as an update. No conversion step was missing, no setting was wrong. Just a number that never changed.
Eight plugins republished
Those already carrying work that could not reach you: Russian and Danish translations for change-password, kolab, login-register, nextcloud, search-filters and two-factor-auth.
Also login-o365 and login-oauth2. Their OAuth2 fixes went out in 4.3.0 under versions that had already been published, which means they had precisely the same problem as the translations.
Go to Admin → Extensions and update them there. Upgrading Tachyon does not bring plugins with it.
Thank you
@lvarnava, again, for asking why instead of assuming it was his mistake.