I talked with Martin Pitt, who let me know that it's intentional behavior that gettext gives precedence to /usr/share/locale over /usr/share/locale-langpack.
apt is one of those 'special' packages in main where the translations shipped with the source package are not stripped at build time. It means that the apt.mo files installed by the language packs are not effective (as we have already figured out). So in case of apt (and a few other special packages) translation updates need to go into the package to make a difference to the users. @Julian: The Xenial template in Launchpad seems to have been updated 2016-03-25 (attached). The easiest (I think) way to get the actual translations is to download them from Launchpad, and simply replace the PO files in the package. https://translations.launchpad.net/ubuntu/xenial/+source/apt/+pots/apt There shouldn't be a need to manually merge as you described. (Possibly I have missed something.) ** Attachment added: "build_po_apt.pot" https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1637801/+attachment/4772060/+files/build_po_apt.pot ** No longer affects: gettext (Ubuntu) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gettext in Ubuntu. https://bugs.launchpad.net/bugs/1637801 Title: Incorrect Russian translation of "apt list --upgradeable" results Status in Ubuntu Translations: Invalid Status in apt package in Ubuntu: Fix Committed Bug description: bor@bor-Latitude-E5450:~$ apt list --upgradeable Вывод списка… Готово build/неизвестно 20161025 all [может быть обновлён до: 20151105] In Russian this means "version 20161025 can be upgraded TO version 20151105) While original English says exactly opposite: bor@bor-Latitude-E5450:~$ LC_ALL=C LANG=C apt list --upgradeable Listing... Done build/unknown 20161025 all [upgradable from: 20151105] Literal translation (that does not require serious phrase change) would probably be "может быть обновлен с" although it sounds also artificial, as in Russian subject is package that is being updated (currently installed), not new version. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: apt 1.2.12~ubuntu16.04.1 ProcVersionSignature: Ubuntu 4.8.0-25.27~16.04.1-generic 4.8.1 Uname: Linux 4.8.0-25-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.1 Architecture: amd64 CurrentDesktop: Unity Date: Sun Oct 30 09:39:47 2016 DistributionChannelDescriptor: # This is a distribution channel descriptor # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor canonical-oem-somerville-trusty-amd64-20140620-0 InstallationDate: Installed on 2015-07-02 (485 days ago) InstallationMedia: Ubuntu 14.04 "Trusty" - Build amd64 LIVE Binary 20140620-04:25 SourcePackage: apt UpgradeStatus: Upgraded to xenial on 2016-10-29 (0 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-translations/+bug/1637801/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp