I believe it is listed as a Limited Multi-Mon Support ("C" Rating) due to my selection for Multi-Monitor Issues. I selected "Significant Issues (C)" after consulting the DR Grade Calculator (found here:
http://www.wsgf.org/grade_calc/). On this page, vert- is listed under Grade C.
I feel the keyword for the grade is "limited." The resolution is detected without issue. Yes, the game is displayed in a less-than-ideal way. However, the resolution is supported, even though it is in a unsatisfactory way.
This game seems to be rendered in a vert- solution. Taking in account the distance of the right cliff from the edge of the screen in my 3x1 screen shot, I would wager that the game most likely take a 4:3 resolution and cuts off the upper and lower thirds to give a zoomed in view of the game field. I was unable to actually get the game to give me a 4:3 resolution when testing the game, so I am unable to fully confirm this at the moment. When I get home tonight, I'll see what I can do to fix that and post to the thread you linked.
Also, I think we recently reached out to Arrowhead about this game. Hopefully, with an open line of communication, we can figure out a solution to give us the proper display solution for the game.