Thanks, i’ve tightened the bolts more than recommended, due to the tight cable curve, the outers are putting more pressure on the callipers than they are supposed to I think.
but the callipers float a bit (will wobble even when tighten up) so once they're tightened up, use a 14mm to centre them on the rims. I think I had a similar issue to what you're finding until I realised that, and now I love the brakes!
i'm sure you know this already, but you can use the 14mm nut on the brake to centre them once they're fitted.