In the transaction there is a "withdraw_type" operation .. in there there is a balanceID (this is NOT an address) .. but you can get the owner key for that balanceid via
blockchain_get_balance <balanceid>the "owner" address is stated in there .. you should be safe just sending the funds back there ..
remark: DO NOT SEND FUNDS TO A BALANCE ID!!!
thanks, I have connect to the sender,
he said he sent with client v0.9
he see cny.transwiser is unregister, and he still sent,
and see the trx history, the receiver is UNKNOWN.
he's client is synced ok.
from my client, I saw the send is UNKNOWN
something must wrong .