I'm out of suggestions but I came to think of one last thing you can try: When you lock the bootloader (as it seems you've done), your fastboot reverts to the CSC fastboot (althoug the ROG 5 bootloader doesn't show it). However, if you try entering fastboot from recovery, maybe it makes a difference for flashing RAW's. Unfortunately I think your flashing issue is related to the totally corrupted firmware on the device (I don't know who sold you this device but they haven't been nice to you). But you may want to give it a try.
Long story short try this:
1 - Boot the device into bootloader (like before)
2 - Do a 'fastboot reboot fastboot" OR go 'fastboot reboot recovery' and select Enter Fastboot Mode from the menu. The device should reboot into a screen actually saying Fastboot (Or Fastboot Mode, I forgot)
3 - Try doing a RAW flash exactly like before. Try with both the WW rom and CN rom. Use the FTM scripts again.
The only other thing I myself would try would be to see if the bootloader can somehow be unlocked from the fake/corrupted rom on your device from the settings menu (i.e OEM Unlock) or via conventional fastboot commands etc (probably not possibe though)
If the above doesn't work, I really can only recommend:
(A) Return the device back to whoever sold it to you (I'm guessing impossible).
(B) Send the device to ASUS and request the firmware to be rebuilt. They will charge you but my guess is it won't be more than US $50 or you may be lucky and they help you out for free
(C) Wait for EDL firehose files for this device to become available. Unfortunately the few people who have it are not sharing it.
Finally, if I were you, I would probably not put any personal files, contacts, passwords or other sensitive data on this device in current state. The firmware on this device looks to be corrupted. I don't know who sold it to you but it may not be safe. I've never seen a ROG 5 with the firmware from your screenshot unless it's something specific to the CN version.