What I did notice from your post is that the demographic that your training is of a particular age. It’s the age bracket that I fit in and I like to considered myself a “seasoned” exerciser.
I don’t know if that word “seasoned” give you any idea, however in your class description.
Words you might use to describe the class you are teaching can related to the level of description. Example–instead of saying beginner, you can say rookie. Something like Rookie Robics.
I hope that gives you some direction.