I like the idea. I've played in a few tabletop games where things like insight checks and perception checks are rolled in secret by the DM, so you don't know by the number if you succeeded or not - you just know what the DM tells you. It might be interesting to have something similar here where you can roll insight if you want and you always get (DC or other) information from it, but you don't get to see your insight roll and the accuracy of that information will vary depending on how well you did.
For people who already play D&D, I think this could be really cool. For folks who don't have a solid grasp of the underlying mechanics of the game, it might be a little confusing, so it would need to be explained in some way.
honestly you don't even have to roll secretly. Simply withhold the DC, and give them something.
for instance if the dc is 18 really high for many reasons. they roll a 12.
'You really can't get a grasp on this person.' or 'The person in question believes what they are saying.'
Example one the person is hard to read, so you don' t know. Example 2 You find out the person believes what they are saying to be true. Weither or not they are lying isn't stated, and left to the player to decide.
