Hey guys, just an FYI I was able to mount the F16 Orion to my J-PEIN mounts with nuts and bolts, ironically just as the manual suggested. I first tried heavy duty velcro, but the throttle was so wobbly it wasn't working. I found a kit on Amazon with the exact bolts (M4) and a variety of screw lengths. I chose the 16mm screws with 2 washers each.
https://www.amazon.com/dp/B07S18NHP5?psc=1&ref=ppx_yo2ov_dt_b_product_details
First thing I did was take the guide rail off and re mount the rails on the top and bottom of the base so that the slot is as aligned as possible to the holes. Then I reattached the rail and adjusted it again to the full throw of the throttle.
I flipped the whole thing upside down on my lap and put the J-PEIN on it. One at a time I slid a M4 nut into the slot, and used the included screwdriver to slowly push the nut into the slot until it lined up with a hole. I then took a 16mm screw and put 2 washers on (big enough not to slip through the J-PEIN channel) and threaded it carefully into the nut, mostly tight but still moveable. Once I got all 4 in and adjusted, I really cranked the screws down.
This thing is SOLID. So, WinWing was right, despite the holes not lining up perfectly, it works great!