What do they call that cloth case that they cover a piano with when transporting it or just protect it from dust? Would just piano case work? Or there is a better term?
I think case usually implies something hard, made of something like plastic; it also implies something that you put the item inside to cover it entirely. A better word is cover when it is soft like a quilt and covers only part of the piano- see e.g. https://www.moverssupplies.com/catalog/product/view/id/309/s/baby-grand-piano-cover-quilted/category/86/
My first reaction was to call it a piano cover, so I did a quick search to make sure there wasn't a more technical term. I'm still not sure there isn't, but if there is, it isn't in general use. Everyone appears to call it a piano cover.