Ideally what is needed is this:
- The Assignment grading table should be configurable at course level, with options to choose which columns will be visible and their order of appearance.
- The Assignment grading table should have a drag and drop feature to re-order columns.
- An Admin setting to define/configure the Assignment grading table structure (visible columns and their order). This structure can then by applied at site level for all courses to maintain consistency across courses.
Therefore, currently the only option seems to make changes to the code. Only changing the CSS will not work in all situations, as the Assignment grading table columns get an automatic id value set. So depending on the options enabled for the assignment, the grading table column ids may be different for different assignments.
This is why changing the Moodle PHP code (as I did in https://moodle.org/mod/forum/discuss.php?d=231488#p1067586) provides a more robust workaround. I also combined related columns into a single column (eg; all submissions are listed in a single column instead of having their own columns). Most of the changes need to happen in the gradingtable.php file in /mod/assign folder. Also, at our institution we've limited the options available when setting up the Assignment dropbox. This again helps in controlling the view of the grading table.