First，using rows/2 can be dangeous in general, as when "rows" is an odd number, it can give you result unexpectd.
Second, you stressed that you are using "internal S matrix". however such matrix does NOT count the periodicity as it has no such information internally. It is only when emepropagate works then the periodicity is counted. Again, the "internal S matrix" only counts the interface s matrix.
To realize your goal, you can duplicate the structure to have [1, (2,3)^2, 4] after [1, (2,3)^1, 4]. Soon the reuse of cells will be available for vote so please check the ix website to vote once it is ready: