BIP0038 is made very computationally difficult to encrypt/decrypt. It was specifically designed to be resistant to hardware-accelerated brute force attacks. That will not be a fruitful attack method unless you simply need to figure out which of 20 passwords was used.

Were you able to decrypt the wallets previously? Were the specific passwords trialed before use?

You might try time-traveling - get a old version of the github bitaddress code from the date of creation to replicate any code flaws and load it back up on the original distro and platform used to make the addresses.