Welcome to the Shotgun community! Just to make sure I’m understanding the issue correctly, your Reviewer is creating a Note with just a single word in it, and that is not triggering the blue dot notification for the Artist that they have new feedback. Is that correct?
In speaking with our team, it sounds like this may be a bug. A blue dot should appear at the corner of the user’s Task card when a new Note has arrived, no matter how short/long the Note. We’ve logged it internally, and I can report back when we have more info.