Does it really matter what the item is called?
In most cases, I think when someone calls a "quilt" something other than "quilt," it is not meant as an insult.
Many people may not know the difference between them - and "Cover" and "Blanket" are quite generic and are used as a term for something one gets under or wraps around oneself to stay warm.
Such as saying "chocolate cake" instead of "Great Grandma's Superlative Triple Chocolate Cake Made Only for Birthdays Cake"
Sometimes some people are more comfortable with a generic term if they are unsure of or don't know a specific one.
I'm getting old(er) - so I'm trying to save my "get my undies in a wad" for things that REALLY matter.