In days long gone by, this problem was well known. The simple solution (for control wires) was to close junctions with turnbuckles of different diameters.
No reason why a similar idea should not be adopted for control rods. Then you can't assemble them incorrectly.
And it those halcyon days, you wiggled your rudder bar and stick when you climbed in, looked over your shoulder to see what the rudder and elevator were doing, and out along the wing to check ailerons. Everybody did that every time.
I suppose by "flaps" (in the original sad story), the writer means "elevators".
D.3