Hello
This is strange installation you have here - according to the logs all partitions are in an LVM volume group split in 3 logical volumes. This means /boot is a directory, not mounted on its own partition. OTOH the boot loader is GRUB1. AFAIK only GRUB2 can boot from a logical volume. Converter also assumes that and expects a partition number for the boot volume.
Either '/boot' is mounted in an unusual way and not recognized by Converter or the GRUB installed is somewhat capable to boot from LVM. Can you post the content of "fstab" to check that?
As a workaround you may try set <callGrubInstall> to false in "converter-worker.xml" and retry the conversion (restart worker service after changing the config). With some luck will succeed. After that boot the VM from a live CD and install grub manually "grub-install /dev/sda" should do the job.
HTH
Plamen