Various fixes in login sources (#10428) (#10429)

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

options/locale/locale_en-US.ini

@@ -374,6 +374,7 @@ user_bio = Biography
 
 form.name_reserved = The username '%s' is reserved.
 form.name_pattern_not_allowed = The pattern '%s' is not allowed in a username.
+form.name_chars_not_allowed = User name '%s' contains invalid characters.
 
 [settings]
 profile = Profile