The extra pair of brackets in your set field steps reveal that you haven't set up these steps correctly:
Set Field [Score By Hole::Gross Score[CourseHole::Par - 1]]
those brackets tell me that you used the button for specifying a repetition number where you should have clicked the "calculated result" specify button.
When Setting up Set Field, there are two Specify buttons that must be clicked. To get Set Field [Table::Field ; Expression], add set field to your script and click the first button (specify target field). Select Table::Field from the list of fields. Do not click the specify button next to the repetition box. Click OK to close this dialog box. Now click the lower specify button (calculated result) and create the expression to the right of the semicolon (;). Do not try to type in the semicolon.
Am I better off create more less complicated relationships than trying to have one humongus relationship that ties everything together. I'm not sure I understand whether you can have multiple relationship graphs without causing overhead or confusing the system.
YES you will be MUCH better off if you use less complicated relationships. Not only will they be much easier to "debug" when something doesn't evaluate as expected, they can evaluate much more quickly with fewer potential screen refresh issues. I almost never reference a table more than twice removed from the current layout's table.