Professors don’t always teach in their actual area of expertise. I had a German language professor whose PhD was in Philosophy and activity published in that field, in English, German and French journals. It does seem like an odd combination, but probably not a lot of students signing up for a class in usability of buttons, even from the fields you would expect to study them .

Yes, hallucination is the now standard term for this, but it’s a complete misnomer. A hallucination is when something that does not actually exist is perceived as if it were real. LLMs do not perceive, and therefor can’t hallucinate. I know, the word is stuck now and fighting against it is like trying to bail out the tide, but it really annoys me and I refuse to use it. The phenomenon would better be described as a confabulation.