What are the consequences for me for not ordering my wife to perform the 'Isha prayer on time, knowing that she did not pray it until after the Fajr adhan, and is my sin like that of one who let the prayer's time expire?

If the wife sleeps after the prayer time has begun, hoping to wake up before the time expires, then there is no sin upon her. However, if she sleeps knowing that she will not wake up until after the time has expired, then she is sinful. She should have prayed within its time according to her ability (standing, sitting, or on her side). If she intentionally slept knowing she would not wake up, she must repent. As for the husband, there is no sin upon him if he hoped she would wake up, but he should have alerted her.