Superprismatic, For the classes #4 and #5, imagine a plane cutting through 1,5,9,10,14, 18, 19,23, 27.
The cells (6) and (8) are in symmetric locations wrt cell (1).
Similarly, for classes #16 and #18, imagine a plane cutting through 2,5,8,11,14,17,20,23,26.
The cells (16) and (18) are in symmetric locations wrt cell (2).
So, the issue raised by witzar and me is: shouldn't we merge classes #4 and #5 because of symmetry? and shouldn't we merge classes #16 and #18 as well? These mergers would shrink your 22 classes to our 20 classes.