FWIW I was the alternate moderator for the now defunct Yahoo Janowski group.Good question though. I have bits and pieces from the site. There is a question on having enough elevator authority at landing. A gurney-flap was discussed, but its not an ideal solution. Some think the aft fuselage should be longer. Maybe 12" longer? Also group discussions on dimensional inconsistencies.
It is an interesting design, but it does need to be carefully reviewed and adjusted before building, I believe.
My friend Alejandro Zapata of Badajoz, Spain is the builder and pilot of EC-ZKB
He powerd it with a modified VW engine of approximately 50 hp. When he first flew his example he could not get it to rotate out of ground effect when at full power. His tecnical advisor then sugested several modification which he implemented.
1) 1cm high gurney flap on the entire span of the underside of the trailing edge of the elevator
2) sealing the gap between the elevator and horizontal stabilizer.
3) lengthening the main landing gear by approximately 15 cm
4 ) lowering the engine thrust line back to the original defined in the plans
With these modifications he corrected the problem and he reports the plane to be docile and well behaved.