Won a NAD case but returned shipment is stuck in customs

I won a NAD case after a full month of back and forth with PayPal and the scummy seller. PayPal asked me to return the items to the address they provided while marking it as “returned cargo” on the box.

I did all of that and marked it on the label too with choosing returned as the type of shipment in the shipper website + insured it and paid for signature required. I paid out of pocket so it arrives to him fast, get my money and close this headache. It was expensive.

It arrived today in his country and the tracking timeline shows that they’re trying to get it out of customs and they might need info from him or me.

I have until Aug 5 until the case closes and I am worried that the scammer will just ignore what they ask from him in order to get it out and just leave the shipment in customs until they ship it back to me. What is the best course of action here to get ahead and prevent something like this from happening?