Although I have not seen this particular instrument, others have constructed similar bowed keyboard instruments based on this concept. In 2013, a company called Antiquity Music exhibited two different concepts like this at the NAMM show in Anaheim. I played both of these.
One looked somewhat similar to the instrument on Viola Organista's web site in that it had a standard flat keyboard and a barrel-shaped housing for the strings.
The other, which they are offering for sale, is the "Wheel Harp." They simplified the mechanism for the instrument by having a barrel-shaped keyboard!
This was quite odd to play - but it worked. You can see it and find out more at their web site at
http://antiquitymusic.com
I imagine you can sample one, if you buy it first!
Les