You can export your play times to json using https://github.com/tallbl0nde/NX-Activity-Log, edit the json, and the import it back in or even edit the times directly in the app. I just tried it out and was able to adjust all sorts of things such as number of times played and for how long. Didn’t try adding any games I haven’t played but it looks it might be possible (though I don’t know where the icon would come from so maybe not.)