Definition of "none the wiser".
Source1.
to fail to understand something. Isabel must have explained her idea three times to me, but I'm afraid I'm none the wiser. If you take the label off the jar and say you made it yourself, your guests won't be any the wiser.
2.
to not be aware of something. The health department gave the restaurant a health warning, but customers were none the wiser.
Usage notes: often said about efforts to be sure that no one is aware: I figured I could just get rid of the stuff, and you'd be none the wiser.
Translating it thus would be :
1. ... και αυτός (ή) πέρα βρέχει / δε σκαμπάζω
2. .. και κανείς δε θα το καταλάβει / πάρει πρέφα / χαμπαριάσει / δε θα το "πιάσει".
If we had more of the text, I think, we could provide you with a more accurate translation. In general though I think these could be used as equivalents. As Vicky indicated, please do read the rules; by providing more information and context you help us help you in return.