The proper localization strings just went live in the Steam game earlier today (except Chinese). As mentioned earlier on this post, there was a problem with the data merge of new strings immediately prior to launch. Now all of the intended strings are in there.
Note that there is currently a bug for multiplayer where some strings in the UI will not be localized, even if the localized string is present. Any such strings *are* localized in single player, but will require some development work to fix in multiplayer.
Thanks again for the bug report!