I tried brailling the cancelled column and row in the matrix as you suggested. I'm not sure that clearly represents what is shown. The cancelled top horizontal row would have inside it another cancellation indicator for the first item in the cancelled column. Would it be clearer to insert a tn stating that the top row and middle column are cancelled in print? or that there is a line drawn through the column and row?
As far as using cancellation symbols in the horizontal row, I don't believe the spaces would end the effect of the indicator.