Converter runs grub2-install on the destination machine but uses whatever files happen to be on the source machine. The error is quite clear:grub2-install: error: /usr/lib/grub/x86_64-efi/modinfo.sh doesn't exist
Check the wanted file on the source; perhaps it is in a different directory. Copy it to where it is needed if so. Try to dry run grub2-install on the source machine (careful to not corrupt it!) to see whether all dependencies are fine and then convert again. Alternatively (and more safely) do these experiments on the target machine if it has not been deleted; you will need to boot from an live ISO to do that.