Those are 3No. 125A fuses (TPN), which will supply 13No. flats. Should I consider dropping from 80A to 63A fuses (even though the calc works with 80A fuses)?The diagram show a 125A fuse on the incoming side of the MSDB boards. That seems a bit low for having 4 * 80A flats on each 125A fuse but maybe that is considered acceptable diversity.
Given you already have the 160A MCCB protecting the board you might want to consider putting links in for those fuses.
What is the difference between a fuse and a link that you are referring to?