No one is talking about whether the ball actually hit the hand or not. Not every ball-to-hand situation is a penalty. The arm was in a natural position and if it hadn't hit the hand, it would've hit the body anyway, so it didn't disrupt the flow of play at all. Balde defended very well in that moment, it's a shame that effort went to waste. Still, since Barca didn't lose points because of it, it's not a big deal. It didn't affect the course of the league in any way.
You're correct, Alejandro Balde didn't do something wrong in this case.His hand replacement was in natural position, referee shouldn't expect whenever the opponent shot the ball, then all the players will place his hand on his back. See in this video, it was a clear Tchouameni's arm wasn't in natural position, but the referee didn't give penalty to Barcelona.
The good thing Barcelona managed to comeback even the referee cheat in this match.
https://www.tiktok.com/@vardridcorruption1/video/7541905783781444894?q=balde%20handball&t=1756028425936