well - not a cotter expert but i use the bikesmith tool on mine - and i usually have to go through the following process to get em to 'stay tight':
-install cotters
-ride
-tighten cotters
-ride
-tighten cotters
-done

beyond that - i would want pics to see the angle issue - and if the ride felt ok and the arms are without play - i would just continue riding and enjoy - as long as the 'angle' doesnt alter your pedaling mechanics to any major detriment to you physically

btw - did you try throwing the original cotters back on - or are they toast?