I think they're meant to be set up like that. They're like the Paul touring cant rather than the neb-retro canti. It gives better clearance for panniers etc but I guess you pay for that with less braking power.
(according to Jan Heine, who knows his stuff) the straddle cable has to be at a 90ยบ angle with the straight line between the pivot and straddle mount on the canti.
Considering this is how VO suggest setting up their cantis I'm not surprised they don't work.