Do I bear any responsibility for the shortfall in the Zakat amount I sent to my aunt in Syria, which was deducted by the transferring entity there?

The original principle is to disburse zakat to the poor of the country where the wealth is located, and it should not be transferred unless there is a need or a benefit. If the zakat payer transfers it without a need or benefit, it is still valid for him, and he is not ordered to return it. The zakat payer must deliver the full amount of zakat, and the expenses of its delivery (such as bank transfer fees) are borne by the owner of the wealth and are not deducted from the zakat, whether these are fees from the intermediary bank or the receiving bank. Therefore, the beneficiary must be compensated for any deducted fees to ensure the full amount of zakat is received.