Yeah my guess is that picking the I am sneaky option at start gives you a higher chance of not getting caught peeping. However far as I can tell this is more of a "feature" or trigger then a skill and since it doesn't prompt in anyway or show up on the MC info, my new game+ save also already picked it before so it's already included. So frankly I wouldn't call it a skill at least not in the way it's implemented at the moment but I guess they can call it whatever they want.It's not a skill just additional rng element,
If there was a useful skill it would be in the cheat menu list fir skills.
Also this new update seems filled with a lot more bugs then previous builds since I pretty much in just a few hours of playing had both Shiori and Emma become so buggy that I decided to try a new game and if this doesn't work I'll just wait for a later patch.
In Shiori's case because of some reason she keeps telling me to babysit her son but the event to do that just won't trigger so she just keeps telling me to watch her son.
For Emma when I was about to go on the friend date to meet her some other event just force started and made me miss the date and I had no way to stop the forced event and there is no way to reschedule the friend date so Emma is never gonna appear in that playthrough.
So gonna try with a new playthrough later on which hopefully will work better.