Yeah, the MBHD script just tries to extract only addresses/keys that actually contain UTXOs... as that should enable recovery of all current coins contained in the wallet.
If it didn't output any keys (as with your other wallet) then it didn't find any UTXOs in your wallet file... was it a zero balance wallet?
Perhaps I need to change the script to output the UTXOs addresses/keys first, and then just dump ALL the addresses/keys that are in the wallet to be safe...
That way the user could try importing/sweeping the UTXO keys first, and if there are still missing coins, they could just import/sweep ALL the keys.
Puzzled by that str to int error though... sounds like it wasn't able to call one of the private key to public address type functions properly or something... hmmmm