CB = 1.x incomprehensible error message for users

Hello,

In the file "default_language.php" we find the error _REGWARN_EMAIL_INUSE
'This e-mail is already registered. If you forgot the password click on "Lost your Password ?" or on "Password Reminder" and new password will be sent to you.'

I can not find this error in the code. In which case this message is displayed?

When I create a new user (or modify a profile) by entering an email address that already exists, I get the message WARNREG_EMAIL_INUSE encoded in en-GB.ini
"This e-mail is already registered. If you forgot your password, click on the <strong>Forgot your password</strong> link and a new password will be sent to you."

Only the first part of the sentence seems appropriate.
I can not find this error in the code. In which case this message is displayed?

thank you

Reviewing source that language string isn't used anywhere. I believe it was used in older releases of CB and is kept for backwards compatibility sake.

Ok, _REGWARN_EMAIL_INUSE is an old code and should be removed from "default_language.php" and others "language.php".

But WARNREG_EMAIL_INUSE is always used.
And for me it's a mistake. Content of "en-GB.ini" and others "xx-XX.ini" should be only: "This e-mail is already registered."

Ok, _REGWARN_EMAIL_INUSE is an old code and should be removed from "default_language.php" and others "language.php".

It's kept for backwards compatibility. You can remove it if you want to, but it won't do any harm leaving it. CB 2.0 will likely be removing all unused strings.

But WARNREG_EMAIL_INUSE is always used.
And for me it's a mistake. Content of "en-GB.ini" and others "xx-XX.ini" should be only: "This e-mail is already registered."

It's a Joomla language string and is based off whatever Joomla language you're using. You need to translate it within Joomla language files.

OK but it's not ok in the "default_language"

What's not ok? That string isn't defined or translated by CB. You could define it in CB if you wanted to, but you should just translate it within Joomla.