Here is my beginner solution. I'm still new to RegEx and originally I didn't know/see that you can tokenize into rows so my answer was extremely inefficient. After some research i got to a much simpler solution!
Step1 - Determined all possible missing values across where the numbers 1-9 were present to get all valid rows Step2 - Got all possible combinations of rows 1-3, 4-6, and 7-9 where numbers 1-9 resided in the 'cubes' Step3 - Of what remained got all possible combinations where the columns contained 1-9.
This involved using append fields tool...and bringing column values into rows for logical testing (1-9).