It doesn’t really matter. The whole “Hide Game from Activity Log” is an effort to stop Nintendo from banning your 3DS if they see anything weird in your log. First of all, we don’t know if they do so, but it’s possible because there’s been a ban wave or two in the past that didn’t involve people being stupid and, say, playing a game online before it’s released. Second, you can (theoretically) just choose not to share data with Nintendo/your 3DS friends to prevent this altogether. Finally, the product code and titleID for injected games of any kind (or any homebrew that you install as a CIA) will always be different from what Nintendo uses, in an attempt to prevent conflicts from legit games from the e-shop. It doesn’t matter if that game you are injecting is a hack or not. Unless you have a specific reason, you can just ignore the titleID and product code fields.