Leftmost is probably a pen, rightmost is definitely a pen and specifically a fountain pen. I've never seen these icons before, and I'm trying to be the fairest I can, and I think rightmost wins at evoking "text editor". But the one exactly in the center wins by a mile. Pen on lined paper, hard to do better.

Same thought. The one on the left just conveys "notes" to me. Middle actually seems to be about a more "well put together" document. A fountain pen by itself doesn't necessarily mean documents to me, but signing them.

As you, never seen these icons in my entire life.