Bug: Wrong variable {Sitename} at the login form

Hello,

there is an incorrect variable in the text of the login form. I have activated the plugin on a german website. The original text above the log in form (shortcode: [wpuf-login] ) in the WordPress language English-US (en_US) reads as follows:

Welcome to XYZ. This site is accessible to approved users only. To be approved, you must first register.

XYZ is the name of the website which is located in WordPress Settings / General / Site Title.

If I change the WordPress language from en_US to German (de_DE), the following text appears above the login form:

Willkommen bei {Sitename}. Diese Website ist nur für zugelassene Benutzer zugänglich. Um zugelassen zu werden, musst du dich zuerst registrieren.

There isn’t shown the Site Title, always {Sitename} (the other parts of the sentence is correct translated).

Can you fix this please?

Currently I am working on a translation for the german language with the .mo/.po-files but this sentence is not into the translation files. I also doesn’t find this sentence into the files wpuf.php, wpuf_functios.php, templates/login-form.php or templates/registration-form.php.

Thanks!