Two points in this mail:
1) Maybe some of you have missed that base-config/po/*po now use plural forms. I noticed that several translation use them but have forgotten to include the appropriate "Plural-Forms" header in their PO file.
Please refer to http://www.gnu.org/software/gettext/manual/html_node/gettext_150.html Most of your languages, if not all, are mentioned here and you will get information about what's adapted to your language.
You can look at fr.po or pt_BR.po for examples.....but the header in both is valid only for these languages.
2) Please test the sid_d-i images
These images of Debian Installer use the latest uploaded packages to unstable. When it comes to i18n/l10n issues, this includes the "new" languagechooser (with one entry per language)
Please test these as much as you can, INCLUDING 2-ND STAGE (display problems occurred in recent weeks).
If you can, install a base system (choose "none" in tasksel), then go to the end of the installation, login as a normal user and check whether output in your language is correct (just try "ls -l foo" for instance...if fileutils are translated in your language). Try "vi foo" and use your language's chacraters in it. Then exit and "cat foo"
You may also try uncommon language+country combinations (Chinese in France for instance....) just to see whether the system of fallback locales works.
URL for sid_d-i images:
http://cdimage.debian.org/pub/cdimage-testing/sid_d-i/
DO NOT use the "daily builds" image on the main d-i page. These are "sarge_d-i". This will probably be clarified after d-i meeting of today 16:00 UTC on #debian-boot (you're welcome to it....it was announce on debian-boot@lists.debian.org)