The misbehaviour is that UI is automatically localized and login's language selection is not taken into account.
On a fresh rebuild, if ever a webclient_fr_FR.properties file is present it is used no matter what I select on the login page (btw, changing lang resets password).
If FR lang. is not declared and thus not available in the drop list, it is still used.
Removing the webclient_fr_FR.properties and restarting makes thing back to EN usage
Environment Server/JVM locale is FR web browser accepts FR first web browser cache is clean bundle is 1.0 server is a rebuilded 1.1.1 OS version
As for what I've cross-read, all default files should be renamed but that causes an issue (not explained) and lots of stack traces at start + CIFS access KO.
It was quite a surprise for me to see that I18N does not work properly in Alfresco. I intended to deploy it in FRench as the users are FR-speaking but I think the start will be in EN. That's a pity indeed however in a technical area people are used to EN.
Because of the issue, the start will be in french, and the whole Alfresco will be in french. You won't notice any word in english, even if you want to .
OK we've found the problem. You need all the "default" properties files (with no locale extension) to be duplicated to have an "_en_US" extension e.g.
webclient.properties
copied to a new file:
webclient_en_US.properties
We tested this and it fixed the problem.
Applogies for this problem. I think we will create an ant task as part of our build scripts that duplicates the default language files to add the _en_US onto each.