No. If we assume that you have to target the wall it would at the very least stop after destroying the wall.
But by RAW, you can’t even cast it on something behind the wall, because you cannot target something (or someone) with a spell if they are behind total cover. Total cover is created by being completely behind an obstacle (like a wall). This counts even if the obstacle is invisible.
Furthermore, if you chose an invalid target for a spell, you still expend the spellslot but there will be no effect. So you'd actually spend a sixth level spell a lot to achieve nothing.
I would not recommend doing it this way, but that’s what the rules say.
I know that it would be out of character, but now I'm trying to make up a plan how this might work. If Mystery can counterspell, then if you send him along while disguised as someone else, it might be possible.
However, as you've said, it would not really accomplish much anyway and Konsi would never do it.
I agree. I normally don't do it, but I still like to know when I'm about to get hit with some of that stuff. There are... some bad memories attached to it.
Yes. See invisibility should work as well. Both are quite annoying to activate when in a fight though.
Edit: TIL that detect magic may not work, because the object has to be visible.