I have more than a little concern as to the overalll competence of whoever did this work.
The handle tie, while not in itself a violation, defies logic. As with GFI breakers, you can't share a neutral between circuits- so this cannot be for a multi-wire branch circuit. So the big question is: WHY?
As for the multiple conductors under one screw, you can probable sort the mess out by grouping the grounds - as many as three are permitted (per UL white book). An easy fix.
