You need to build your decision table with both role type and criticality as your input. You then need to 3 scenerios (more if you want to break role type down further)
1. Role type = composite and criticality is * then approver is approver1
2. Role type <> composite (covers and others) and criticality is high then approver is approver2
3. Role type <> composite and critucality <> high then approver is approver2
break your requirements down to single lines for you if statements and you will find it easier to prepare decision tables