I don't know anything about CAS authentication but that message is defined in auth/cas/CAS/CAS.php so you could change the message there. Be aware that you may then see the "User invalid, verify" message if there were other errors that would previously have shown "Internal script failure".
Authentication
howto modify Error: Internal script failure message
토론이 끝났습니다. 더 이상 답변할 수 없습니다.