you tool stopped to work , even umodel not working the only way to export it as i find it with quickbms only
the original ue4 pak bms script, doing to job very well , let me tell you way its may even help you to upgrade your script
first what your script not doing is if the aes key changed its not request any new aes info that how i fixed your script
the original bms script ask the aes key if he detect aes inside the pak normally its normal operation to do
it was very clearly that the script you done not going to hold for a long term , lets call it outdated.