To stop the trigger's mainspring from forcing the rear trigger up, the mainspring has to come to a stop on something. Ideally, that is the trigger plate. That takes some careful filing to get the mainspring to have lots of force on the trigger, but then stopping allowing the trigger to float, and under the inertia of having been set and fired to continue up to strike the sear arm with sufficient force to fire the lock.
Alternatively, yes, you can install a screw through the trigger plate to stop the downward force of the mainspring, thereby letting the rear trigger come to rest without interfering with the sear. That screw must be adjusted with the trigger guard off the rifle..it's not something that is easy to access with the guard in place, though I suppose you could drill a hole big enough for your adjustment tool, through the trigger guard...ugly.