Sold tickets back in December - transferred them the same day to the email address given to me. We'll its been over a month since the transfer and the buyer hasn't accepted them yet. I did reach out to the buyer with the email I sent the tickets to and so far No Response. Now, Im getting to the point where I would like and now have time to attend this event. What is the penalty I would incur if I did reverse the transfer? I don't know if this person saw the email, has changed their mind or has completely forgot about this purchase. Like I mentioned, I did transfer these the same day and got confirmation for that as well.
You will get a 100% penalty if you cancel the transfer.
Keep all of your transfer documentation that shows that you transferred to the correct email address and confirm your sale. You will get paid regardless if the buyer accepts the tickets or not.
The OP seemed to be more concerned about what would happen if he kept the tickets. He stated that he now has the time and would like to attend the event. He wants to know what the penalty would be so he can weigh the cost of canceling the transfer and going to the event himself.
One advice I would give to the OP is not to contact the buyer. It will turn out bad and against StubHub policy. The buyer is in no position to negotiate any deal. Anything he does will most likely benefit him and hurt you.
I have had regrets also, and ended up buying another set of tickets from StubHub. Yes, it was painful.