I have a photo from Peter Grosz that shows a set of mounting "triangles" for the lower wings. They look almost the same as the museum photo, but the ones in this photo are almost a wider equilateral triangle with a base at the mounting to the fuselage as compared to a narrow sloped triangle in the museum reconstruction. It appears that tubes ran across the top of the fuselage through a hole at the "point" or top of the triangle. The outside ends of the tubes had a bracket that folded in a U shape on top and bottom of the wing at the spar location and bolts threaded through that bracket to hold the wing to the mounting system.
I need to get an image hosting platform sorted out before I post this, but maybe could email the photo to you?
By the way, I sent some of the photos to the author of Wings of Serbia but can't recall at this moment if that particular one made it to the book. It is a great book and one of the best sources of information on the Lohners.
As an added FYI, you may want to look at the shape of the side view of L127 in the Windsock Datafile. The fuselage plans in the book and that photo don't completely match. It is hard to see, but the top of the rear fuselage seems to rise up instead of extend straight out from the curve behind the engine tower. At least that is how it appears to me.
Tnarg