Current questions and answers regarding the map editor.

Maybe because I set the coordinates, and it's hidden in the city?

Where did you set the coordinates?

I'm entering the scripted in-game name of the hero into the target.

Without quotes? Where did you find the hero's name, in ObjectProperties?

Is it possible to lower a specific skill for a hero?

I don't think so. You can take away experience and rely on randomness. Or take away a lot of experience, enough so that the desired skill is definitely lowered.))

Is it possible to teach a hero a non-standard spell?

I don't know.