If you want to be able to stop a random event executor mid-execution, you will probably have to override its shouldActivate method with:
public boolean shouldActivate() {
return super.shouldActivate() && running;
}
where running is a boolean you create in the solver itself. Then you could stop it by setting running to false.
Interrupting it wont do any good. Scripts are used to being interrupted (eg. by randoms) and will continue on the very next loop.
FrostBug's post in Terminate random event script was marked as the answer