This text is particularly confusing if you import several certificates at once, because it is then unclear which password is required. For this, the name of the file to be imported should be mentioned in the question. But this is not a typical usecase, so maybe not.
If you enter a wrong password in a window, the error message will only be given after you have answered all requests for the transport passwords.
If we should want to support importing several of these at once, that is impractical.
Suggestion for easier language: "Bitte vergeben Sie ein neues Passwort für das Zertifikat" "Please assign a new password for the certificate"
But at least change passphrase to password in German, to keep it consistent.