I'm not sure I understand your problem exactly, but if you want to make the YearEventKey_Grouping go from
2009 Submission-2010 Submission to 12-13, then this is how you can do it.
From Table2; //If this table is in memory, then you should use Resident Table2; in stead of From.
mapsubstring('YearEventIDMap',YearEventKey_Grouping) as YearEventKey_Grouping,
From Table1; //need to replace this line with the source for table 1.
Hope this helps