It's small consolation, but as others have said, don't be too hard on yourself. You got current, prepared for your interview and after 4 years, there wasn't much more you could have done.
To be honest after all that time, I am impressed that you did so well in all other aspects of the sim check. It's always a high pressure situation, hightended considerably after 4 years of waiting.
Did you get a de-brief afterwards? No chance of a frank conversation, do all you can to be even more attractive to them and ask to be re-considered at a later date? They must have liked the look of you to give you an interview.
I feel your pain.