It seems that on extended screens (e.g User.edit, but I saw the same with External Files screen), translation is applied partially as you can see below: tab ‘New User’, field ‘New Password’, button ‘add’ for roles, but ‘ajouter’ for substituted users.
I checked the messages_fr file and item ‘password’ for instance is there yet. Strangely sometimes translation is found sometimes not.
Attached a sample project.
testcuba.zip (131.0 KB)