Hi! Sadly with the other part I stucked without any clue. From the jobs (jenkins/war/work/job/ExampleName ) I see this example:
<folderViews class="com.cloudbees.hudson.plugins.folder.views.DefaultFolderViewHolder">
<views>
<hudson.model.AllView>
<owner class="com.cloudbees.hudson.plugins.folder.Folder" reference="../../../.."/>
<name>All</name>
<filterExecutors>false</filterExecutors>
<filterQueue>false</filterQueue>
<properties class="hudson.model.View$PropertyList"/>
</hudson.model.AllView>
When I change it manually ,I see the change. But as this is generated, change needs to be happen somewhere else. I found this similar example in work\config.xml:
<hudson.model.AllView>
<owner class="hudson" reference="../../.."/>
<name>all</name>
<filterExecutors>false</filterExecutors>
<filterQueue>false</filterQueue>
<properties class="hudson.model.View$PropertyList"/>
</hudson.model.AllView>
This is where other part of the Jenkins correctly converted All -> Tous . In this scenario the src/main/resources/hudson/model/Messages_fr.properties file used
Hudson.ViewName=Tous
In javadoc I see that Hudson has this key value : 
But in the Folder plugin Doc I did not find this Key option and my knowledge is very limited to understand how to implement it to the plugin.
In AllView change did not help, I tried other property files in the plugin&core but none of them changed the value. Any new idea welcome.
I mean…
I think the AllView "All" created by AbstractFolder will be renamed to "all" by DefaultFolderViewHolder when Jenkins is restarted, and the localized display name will be displayed from then on.
If that is true, then the proper fix would be to make AbstractFolder create the view as "all" in the first place so that DefaultFolderViewHolder wouldn't have to rename it later, and the display name would be localized without needing a Jenkins restart.