It shouldn't be too difficult to get a foot that works with the Kenquilt. I don't have one in front of me, and there's only one video that shows the foot in operation. It appears to be a high shank foot (measure it). The video shows a foot similar to the first link. Most of the needle bar, and presser bar centerlines are so close that any foot that the needle will go through will work. The Kenquilt does not have a "hopping" pressure bar, so the foot needs to have some vertical adjustment, rather than fixed.
They call it a "darning foot," but most darning feet are hopping. If the needle bar screw is located properly, a hopping foot could be made to work. What is referred to as an embroidery foot more closely describes what is shown on the long arm parts site. If the needle bar screw is located such that a traditional hopping, darning foot will work, I'd think the Kenquilt would benefit from this.
The second link shows a quilting foot, which is sometimes referred to as a "bowl foot," because of the shape. This would work as well as long as the needle penetrates without needle strike.
There's no reason a ruler foot such as the Westalee or Clarity wouldn't work either. Both have vertical adjustment.
You can find a foot that works. You just have to do a little legwork.
https://www.sewingpartsonline.com/qu...er-160342.aspx
https://www.sewingpartsonline.com/qu...inger-qs1.aspx