If I had weather helm on both tacks I would indeed be looking very carefully at the rig.
we were on the no2 jib, and sheeting was consistent, its was on every tack that port had weather helm, starboard was finger tip control.
If it was a foil or rudder rake, I would expect to feel it on both tacks, but I'm not (cassette rudders by the way, so no chance of kicking back.
It seems to be pointing towards a foil twisting when loaded in a particular direction, time for a close look at the rudder cassettes and daggerboard cases for cracks