Hi,
Well, even if we add it in the future, that won't explain why you got the issue in the past. And even if you get the issue again in the future, it could still be a mistery. If it was added by a hack, then if it was done through a direct MySQL query, these fields wouldn't be filled.
All that would tell you is who added it when if it was really added by you through the interface.
But yes, we'll look at actions logging in the future. And not just for that, but for orders, customers, products, etc.