If they are not willing to do this, then it may be because of the associated risks. People may bombard them with demands to do the same for them, and use this situation to force OTM to do it. Don't forget not all users will have good intentions like you! Moreover, OTM cannot guarantee that the problem may go further if they told you (i.e. abusive confrontations).

Someone on the other thread mad a really good suggestion.
If they can pm the person(s) I traded to in game and let them know I was looking for the stuff.
If they told me they had done that, didn't mention any names to me I would be happy.
I just want the opportunity to have the stuff handed back to me.
If they didn't return items, then I perfectly understand that all trades are final.
How about a butter reason?
Um they can't tell you because of the butter they are eating.
How did I do?
On serious note it is player-error but this info isn't some breach of policy, and it would take a quick survey using tools you have. Seems harmless not to just say hey this went to this guy, that went to that.
True tea, butter is not really the right thing to ask for hahaha