Hi! Yes, I am talking about this schema type.
"It seems this can be a problem with SEO if questions are selected randomly."
I use CreativeWork schema on my randomizer:
litfan.ru/besplatnyj-generator-idej-dlja-sjuzheta/ . And it works fine, because I also add @type":"ListItem" schema with first 100 results of randomizer, so the search engines could see half of results in a fixed order. So I guess, you can include quiz questions in a fixed order in ListItem as well (if it's a right markup for quizzes).