This isn't really an error, until this point, this output is normal. Most OsxAptio problems manifest in a verbal error like "Cannot allocate memory".
No displayed error probably means boot.efi refuses to start kernel (for example using imac pro board id without manually enabling it), or a very early kernel panic that do not even get displayed.
I checked your efi and you are indeed trying to use imacpro, however, to boot the installer, you must manually enable imacpro boardid IN THE INSTALLER USB. It might be done, but I don't recommend it, try installing with iMac17,1, and switch to iMacPro once you got a bootable system and you can edit the supported boardids.