You need to call sort in your for condition It only needs a small change to sort out

foreach my $key ( keys %event_hash ) {
    print $key, "\n";
    for my $key2 ( sort { $a <=> $b } keys %{ $event_hash{$key} } ) { 
+   
    
    print "$key2=$event_hash{$key}{$key2}\n";
    }
     print "\n";
 }
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