I’m trying to do the same thing. I got the CLITool to think it is working but all I see on my NCS314-8C is darkness, other than a very quick flash of the LEDs when power is first applied to the PI HAT adaptor shield. Have you at least gotten the first 6 nixies working? The help response for the CLITool says [digits] - and six or nine digits which makes me hopeful that there is a chance for it to work, but I’ve just got a blank clock.
Everything works fine when I take the Raspberry Pi and adaptor off and plug in the Arduino, so something is either wrong in the adapter itself or in the software.
I realize this post is over 2 years old, and there have been no replies, so I’ll start a new post and see if anyone has tried this recently.