Premise: It is impossible for a character to not succeed (do) something substantial, as any action is inherently substantial.

If any action by itself is substantial then >

"Character A blinked." or "Character A breathed." Would be a substantial action by itself? That is without any other action before or after to give it meaning?

I don't believe so. Though what I had meant by then was more in the lines of a worthy post, which is one that made sense, advanced the story/characters and resulted in something concrete.

I will read tomorrow the changes done to decide if any further alteration is needed.