Overriding a message does not work with lang="en"

Version 4.0.13, I use the code below to override the translation of a message. If the parent field is loaded withlang="fr" or without the lang attribute, it works correctly, but if I load it with lang="en" it shows the default “No results found” message. I expect it to override the default message anyway, but it looks like the “language” section is ignored when lang="en" is set. You can see an example on Codepen.
LLABTM (Looks Like A Bug To Me).
Any suggestion / workaround?

    language: {
        noResults: function () {
            return 'Merci de taper une adresse email pour inviter un nouveau utilisateur';

P.S. I’m going to handle the English translation of the message once I’ll get the option working.

edit: added a test case without the lang attribute.