.First of all, this isn't a catastrophic failure by any means. It is very fixable and may take some work, but certainly doable.
suggest you look up a parts break down for your engine so you can see how that "wrong screw" removal fits in the lower foot section. Then you can maybe work with a awl to see if you can realign it up where it is supposed to fit and avoid opening the lower foot to fix. Some times that works. But worst case is you'll have to open the lower foot to get it back in place.
It is the pivot pin for the clutch dog that shifts the forward, neutral, reverse gears...