So, not having a good day. I tried installing GhostBSD on a new partition, by choosing UFS Custom Disk option. Even though I selected a new partition and the appropiate mountpoints for GhostBSD, instead of installing there it basically overwrote my MAC OS UFS partition. The installation failed, so now not only have I lost important data, but not even GhostBSD is running.

You should really put some checks in place to at least alert users. I understand that dual boot isn't even possible right now under UEFI, but I did not get any warnings... Also, at the beginning of the installation, there was a weird message at the bottom: [: UEFI Unrecognized character

Oh, I am very sorry about that and I never got a successful installation on a Mac system with GhsotBSD it is true for the installer should warn you that it is not supporting UEFI dual booting.