Can't boot after enabling FileVault macOS Sierra
First if all, thanks to @klanomath or I likely would still be assuming the wrong issue. He was correct that the data was never actually encrypted due to FileVault's incompatibility with CloverUEFI. I used a Mavericks install USB, and used Terminal from inside it to confirm that the data was not encrypted, followed by using the "Turn Off Encryption..." option for the disk in disk utility, and immediately rebooting after double checking that the disk was not actually actively decrypting. 

I now have access to my Sierra install again, and will shortly test my Sierra and El Capitan recovery partitions to see if they are working.